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The History of Visual basic

2015-10-03T20:36:00.002-07:00

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Visual Basic

This article is about the Visual Basic language shipping with Microsoft Visual Studio 6.0 or earlier. For the Visual Basic language shipping with Microsoft Visual Studio .NET or later, see Visual Basic .NET.

\Visual Basic is a legacy third-generation event-driven programming language and integrated development environment (IDE) fromMicrosoft for its COM programming model first released in 1991. Microsoft intended Visual Basic to be relatively easy to learn and use.^[1]^[2] Visual Basic was derived from BASIC and enables the rapid application development (RAD) of graphical user interface (GUI)applications, access to databases using Data Access Objects, Remote Data Objects, or ActiveX Data Objects, and creation of ActiveX controls and objects.

Visual Basic
Major implementations


Paradigm	Object-based and Event-driven
Developer	Microsoft
First appeared	1991; 24 years ago
Stable release	6.0 / 1998; 17 years ago
Typing discipline	Static, strong
OS	Microsoft Windows and MS-DOS
Website	msdn.microsoft.com/en-us/vstudio/ms788229.aspx
Microsoft Visual Studio
Influenced by
BASIC
Influenced
Visual Basic .NET, Gambas, Xojo and Basic4ppc

A programmer can create an application using the componentsprovided by the Visual Basic program itself. Over time the community of programmers developed third party components.^[3]^[4]^[5]^[6]^[7] Programs written in Visual Basic can also use the Windows API, which requires external function declarations.

The final release was version 6 in 1998 (now known simply as Visual Basic). Though Visual Basic 6.0 IDE is unsupported as of April 8, 2008, the Visual Basic team is committed to "It Just Works" compatibility for Visual Basic 6.0 applications on Windows Vista, Windows Server 2008including R2, Windows 7, Windows 8, and Windows 8.1.^[8] In 2014 there are tens of thousands of developers who still prefer Visual Basic 6.0 over Visual Basic .NET.^[3]^[9] Moreover, in recent years some developers lobbied aggressively for a new version of Visual Basic 6.0.^[10]^[11]^[12] ^[13] A dialect of Visual Basic, Visual Basic for Applications (VBA), is used as a macro or scripting language within several Microsoft applications, including Microsoft Office.^[14]

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Language features[edit]

Like the BASIC programming language, Visual Basic was designed to accommodate a steep learning curve. Programmers can create both simple and complex GUI applications. Programming in VB is a combination of visually arrangingcomponents or controls on a form, specifying attributes and actions for those components, and writing additional lines ofcode for more functionality. Since VB defines default attributes and actions for the components, a programmer can develop a simple program without writing much code. Programs built with earlier versions suffered performance problems, but faster computers and native code compilation has made this less of an issue.^{[citation needed]}

Though VB programs can be compiled into native code executables from version 5 on, they still require the presence of around 1 MB of runtime libraries. Core runtime libraries are included by default in Windows 2000 and later, but extended runtime components still have to be installed. Earlier versions of Windows (95/98/NT), require that the runtime libraries be distributed with the executable.

An empty form in Visual Basic 6.

Forms are created using drag-and-drop techniques. A tool is used to place controls (e.g., text boxes, buttons, etc.) on the form (window). Controls have attributes andevent handlers associated with them. Default values are provided when the control is created, but may be changed by the programmer. Many attribute values can be modified during run time based on user actions or changes in the environment, providing a dynamic application. For example, code can be inserted into the form resize event handler to reposition a control so that it remains centered on the form, expands to fill up the form, etc. By inserting code into the event handler for a keypress in a text box, the program can automatically translate the case of the text being entered, or even prevent certain characters from being inserted.

Visual Basic can create executables (EXE files), ActiveX controls, or DLL files, but is primarily used to develop Windows applications and to interface database systems. Dialog boxes with less functionality can be used to provide pop-up capabilities. Controls provide the basic functionality of the application, while programmers can insert additional logic within the appropriate event handlers.

For example, a drop-down combination box automatically displays a list. When the user selects an element, an event handler is called that executes code that the programmer created to perform the action for that list item.

Alternatively, a Visual Basic component can have no user interface, and instead provide ActiveX objects to other programs via Component Object Model (COM). This allows for server-side processing or an add-in module.

The runtime recovers unused memory using reference counting, which depends on variables passing out of scope or being set to Nothing, avoiding the problem of memory leaks common to other languages. There is a large library of utility objects, and the language provides basic object oriented support. Unlike many other programming languages, Visual Basic is generally not case sensitive—though it transforms keywords into a standard case configuration and forces the case of variable names to conform to the case of the entry in the symbol table. String comparisons are case sensitive by default.

The Visual Basic compiler is shared with other Visual Studio languages (C, C++). Nevertheless, by default the restrictions in the IDE do not allow creation of some targets (Windows model DLLs) and threading models, but over the years, developers have bypassed these restrictions.

Characteristics[edit]

The code windows in Visual Basic, showing a Function using the If, Then, Else and Dim statements.

The following Visual Basic traits differ from C-derived languages:

Statements tend to terminate with keywords, such as "End If", instead of using "{}"s to group statements.
Multiple variable assignment is not possible. A = B = C does not imply that the values of A, B and C are equal. The boolean result of "Is B = C?" is stored in A. The result stored in A would therefore be either false or true.
Boolean constant True has numeric value −1.^[15] This is because the Boolean data type is stored as a 16-bit signed integer. In this construct −1 evaluates to 16 binary 1s (the Boolean value True), and 0 as 16 0s (the Boolean valueFalse). This is apparent when performing a Not operation on a 16 bit signed integer value 0, which returns the integer value −1, in other words True = Not False. This inherent functionality becomes especially useful when performing logical operations on the individual bits of an integer such as And, Or, Xor and Not.^[16] This definition of True is also consistent with BASIC since the early 1970s Microsoft BASIC implementation and is also related to the characteristics of CPU instructions at the time.
Logical and bitwise operators are unified. This is unlike some C-derived languages (such as Perl), which have separate logical and bitwise operators. This again is a traditional feature of BASIC.
Variable array base. Arrays are declared by specifying the upper and lower bounds in a way similar to Pascal andFortran. It is also possible to use the Option Base statement to set the default lower bound. Use of the Option Base statement can lead to confusion when reading Visual Basic code and is best avoided by always explicitly specifying the lower bound of the array. This lower bound is not limited to 0 or 1, because it can also be set by declaration. In this way, both the lower and upper bounds are programmable. In more subscript-limited languages, the lower bound of the array is not variable. This uncommon trait does exist in Visual Basic .NET but not in VBScript.

OPTION BASE was introduced by ANSI, with the standard for ANSI Minimal BASIC in the late 1970s.

Relatively strong integration with the Windows operating system and the Component Object Model. The native types for strings and arrays are the dedicated COM types, BSTR and SAFEARRAY.
Banker's rounding as the default behavior when converting real numbers to integers with the Round function.^[17] ? Round(2.5, 0) gives 2, ? Round(3.5, 0) gives 4.
Integers are automatically promoted to reals in expressions that involve the normal division operator (/) so that division of one integer by another produces the intuitively correct result. VB provides a specific integer divide operator (\) that does truncate.
By default, if a variable has not been declared or if no type declaration character is specified, the variable is of typeVariant. However this can be changed with Deftype statements such as DefInt, DefBool, DefVar, DefObj,DefStr. There are 12 Deftype statements in total offered by Visual Basic 6.0. The default type may be overridden for a specific declaration by using a special suffix character on the variable name (# for Double, ! for Single, & for Long, % for Integer, $ for String, and @ for Currency) or using the key phrase As (type). VB can also be set in a mode that only explicitly declared variables can be used with the command Option Explicit.

History[edit]

Alan Cooper created the drag and drop design for the user interface of Visual Basic.

VB 1.0 was introduced in 1991. The drag and drop design for creating the user interface is derived from a prototype form generator developed by Alan Cooper and his company called Tripod.^{[citation needed]}^[discuss] Microsoft contracted with Cooper and his associates to develop Tripod into a programmable form system for Windows 3.0, under the code name Ruby (no relation to the later Ruby programming language).

Tripod did not include a programming language at all. Microsoft decided to combine Ruby with the Basic language to create Visual Basic.

The Ruby interface generator provided the "visual" part of Visual Basic and this was combined with the "EB" Embedded BASIC engine designed for Microsoft's abandoned "Omega" database system. Ruby also provided the ability to loaddynamic link libraries containing additional controls (then called "gizmos"), which later became the VBX interface.^[18]

Timeline description[edit]

Basic for MS-DOS

VB DOS icon

Project 'basic Thunder' was initiated in 1990.^[19] Thunder persisted through to the last release of Visual Basic in the name of the primary internal function, "ThunderRTMain".
Visual Basic 1.0 (May 1991) was released for Windows at the Comdex/Windows World trade show in Atlanta, Georgia.

Visual Basic 1.0 for DOS was released in September 1992. The language itself was not quite compatible with Visual Basic for Windows, as it was actually the next version of Microsoft's DOS-based BASIC compilers, QuickBASIC and BASIC Professional Development System. The interface used a Text user interface, using extended ASCII characters to simulate the appearance of a GUI.

Visual Basic 2.0 was released in November 1992. The programming environment was easier to use, and its speed was improved. Notably, forms became instantiable objects, thus laying the foundational concepts of class modules as were later offered in VB4.
Visual Basic 3.0 was released in the summer of 1993 and came in Standard and Professional versions. VB3 included version 1.1 of the Microsoft Jet Database Engine that could read and write Jet (or Access) 1.x databases.
Visual Basic 4.0 (August 1995) was the first version that could create 32-bit as well as 16-bit Windows programs. It has three editions; Standard, Professional, and Enterprise. It also introduced the ability to write non-GUI classes in Visual Basic. Incompatibilities between different releases of VB4 caused installation and operation problems. While previous versions of Visual Basic had used VBX controls, Visual Basic now used OLE controls (with files names ending in .OCX) instead. These were later to be named ActiveX controls.
With version 5.0 (February 1997), Microsoft released Visual Basic exclusively for 32-bit versions of Windows. Programmers who preferred to write 16-bit programs were able to import programs written in Visual Basic 4.0 to Visual Basic 5.0, and Visual Basic 5.0 programs can easily be converted with Visual Basic 4.0. Visual Basic 5.0 also introduced the ability to create custom user controls, as well as the ability to compile to native Windows executable code, speeding up calculation-intensive code execution. A free, downloadable Control Creation Edition was also released for creation ofActiveX controls. It was also used as an introductory form of Visual Basic: a regular .exe project could be created and run in the IDE, but not compiled.
Visual Basic 6.0 (Mid-1998) improved in a number of areas^[20] including the ability to create web-based applications. Visual Basic 6.0 extended support ended in March 2008; however, primary components of the Visual Basic 6development environment run in all 32-bit versions of Windows up to and including 8.1.^{[citation needed]}
Mainstream Support for Microsoft Visual Basic 6.0 ended on March 31, 2005. Extended support ended in March 2008.^[21] In response, the Visual Basic user community expressed its concern and lobbied users to sign a petition to keep the product alive, to no avail.^[22]

Derivative languages[edit]

Microsoft has developed derivatives of Visual Basic for use in scripting. Visual Basic itself is derived heavily from BASIC, and subsequently has been replaced with a .NET platform version.

Some of the derived languages are:

Visual Basic for Applications (VBA) is included in many Microsoft applications (Microsoft Office), and also in many third-party products like SolidWorks, AutoCAD, WordPerfect Office 2002, ArcGIS, Sage 300 ERP, and Business Objects Desktop Intelligence. There are small inconsistencies in the way VBA is implemented in different applications, but it is largely the same language as Visual Basic 6.0 and uses the same runtime library. Visual Basic development ended with 6.0, but in 2010 Microsoft introduced VBA 7 to provide extended features and add 64-bit support.^[23]
VBScript is the default language for Active Server Pages. It can be used in Windows scripting and client-side web pagescripting. It resembles VB in syntax, but is a separate language—executed by vbscript.dll instead of the VB runtime. ASP and VBScript should not be confused with ASP.NET, which uses the .NET Framework for compiled web pages.
Visual Basic .NET is Microsoft's designated successor to Visual Basic 6.0, and is part of Microsoft's .NET platform. Visual Basic .NET compiles and runs using the .NET Framework. It is not backwards compatible with Visual Basic 6.0. An automated conversion tool exists, but fully automated conversion for most projects is impossible.^[24]
OpenOffice Basic is a Visual Basic compatible interpreter that originated in StarOffice office suite.
Gambas is a Visual Basic inspired free software programming language for the Linux operating system. It is not a clone of Visual Basic, but it does have the ability to convert Visual Basic programs to Gambas.
WinWrap Basic is a third-party VBA variant used with various software, and available for programmers to use to build a macro facility into their programmes.
LotusScript is a VBA variant available in Lotus SmartSuite and Lotus Notes.
Later versions of Corel WordPerfect Office implement access to VBA as one of the macro/scripting languages, the other major ones being CorelScript and PerfectScript
Earlier versions of Microsoft Word use a variant of Visual Basic called WordBasic

Performance and other issues[edit]

Earlier versions of Visual Basic (prior to version 5) compiled the code to P-Code only. The P-Code is interpreted by the language runtime. The benefits of P-Code include portability and smaller binary file sizes, but it usually slows down the execution, since having a runtime adds an additional layer of interpretation.

Visual Basic applications require Microsoft Visual Basic runtime MSVBVMxx.DLL, where xx is the relevant version number, either 50 or 60. MSVBVM60.dll comes as standard with Windows in all editions after Windows 98. A Windows 95 machine would however require inclusion with the installer of whichever dll was needed by the program.

Visual Basic 5 and 6 can compile code to either native or P-Code but in either case the runtime is still required for built in functions and forms management.

Criticisms levelled at Visual Basic editions prior to VB.NET include:^[25]

Versioning problems associated with various runtime DLLs, known as DLL hell
Poor support for object-oriented programming^[26]
Inability to create multi-threaded applications, without resorting to Windows API calls
Variant types have a greater performance and storage overhead than strongly typed programming languages
Dependency on complex and fragile COM Registry entries^[27]

Legacy development and support[edit]

All versions of the Visual Basic development environment from 1.0 to 6.0 were retired by Microsoft by 2008, and are therefore no longer supported. The associated runtime environments are also unsupported, except for the Visual Basic 6 core runtime environment, which Microsoft officially supports for the lifetime of Windows 8^[28] and Windows 10.^[29] Third party components that shipped with Visual Studio 6.0 are not included in this support statement. Some legacy Visual Basic components may still work on newer platforms, despite being unsupported by Microsoft and other vendors.

Documentation for Visual Basic 6.0, its application programming interface and tools is best covered in the last MSDNrelease before Visual Studio.NET 2002. Later releases of MSDN focused on .NET development and had significant parts of the Visual Basic 6.0 programming documentation removed as the language evolved, and support for older code ended.

Although vendor support for Visual Basic 6 has ended, and the product has never been supported on the latest versions of Windows, key parts of the environment appear to still work on newer platforms. It is possible to get a subset of the development environment working on 32-bit versions of Windows Vista, Windows 7 and Windows 8; the primary limiting factor on 64-bit editions of Windows is the 16-bit setup program.

Example code[edit]

The following code snippet displays a message box saying "Hello, World!" as the window loads:

Private Sub Form_Load()
    ' Execute a simple message box that says "Hello, World!"
    MsgBox "Hello, World!"
End Sub

This snippet makes a counter that moves up 1 every second (a label and a timer control need to be added to the form for this to work) until the form is closed or an integer overflow occurs:

Option Explicit
Dim Count As Integer
Private Sub Form_Load()
    Count = 0
    Timer1.Interval = 1000 ' units of milliseconds
End Sub
Private Sub Timer1_Timer()
    Count = Count + 1
    Label1.Caption = Count
End Sub

The History of Mathematics

2015-01-27T07:45:00.001-08:00

Mathematics

From Wikipedia, the free encyclopedia

This article is about the study of topics, such as quantity and structure. For other uses, see Mathematics (disambiguation).

"Math" redirects here. For other uses, see Math (disambiguation).

Euclid (holding calipers), Greek mathematician, 3rd century BC, as imagined by Raphael in this detail fromThe School of Athens.^[1]

Mathematics (from Greek μάθημα máthēma, “knowledge, study, learning”) is the study of topics such as quantity (numbers),^[2]structure,^[3] space,^[2] and change.^[4]^[5]^[6] There is a range of views among mathematicians and philosophers as to the exact scope anddefinition of mathematics.^[7]^[8]

Mathematicians seek out patterns^[9]^[10] and use them to formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proof. When mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature. Through the use of abstraction and logic, mathematics developed from counting, calculation,measurement, and the systematic study of the shapes and motions of physical objects. Practical mathematics has been a human activity for as far back as written records exist. The research required to solve mathematical problems can take years or even centuries of sustained inquiry.

Rigorous arguments first appeared in Greek mathematics, most notably in Euclid's Elements. Since the pioneering work of Giuseppe Peano (1858–1932), David Hilbert (1862–1943), and others on axiomatic systems in the late 19th century, it has become customary to view mathematical research as establishing truth by rigorous deduction from appropriately chosen axioms and definitions. Mathematics developed at a relatively slow pace until the Renaissance, when mathematical innovations interacting with new scientific discoveries led to a rapid increase in the rate of mathematical discovery that has continued to the present day.^[11]

Galileo Galilei (1564–1642) said, "The universe cannot be read until we have learned the language and become familiar with the characters in which it is written. It is written in mathematical language, and the letters are triangles, circles and other geometrical figures, without which means it is humanly impossible to comprehend a single word. Without these, one is wandering about in a dark labyrinth."^[12] Carl Friedrich Gauss (1777–1855) referred to mathematics as "the Queen of the Sciences".^[13] Benjamin Peirce (1809–1880) called mathematics "the science that draws necessary conclusions".^[14] David Hilbert said of mathematics: "We are not speaking here of arbitrariness in any sense. Mathematics is not like a game whose tasks are determined by arbitrarily stipulated rules. Rather, it is a conceptual system possessing internal necessity that can only be so and by no means otherwise."^[15] Albert Einstein (1879–1955) stated that "as far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."^[16] French mathematician Claire Voisin states "There is creative drive in mathematics, it's all about movement trying to express itself." ^[17]

Mathematics is used throughout the world as an essential tool in many fields, including natural science, engineering, medicine, finance and the social sciences. Applied mathematics, the branch of mathematics concerned with application of mathematical knowledge to other fields, inspires and makes use of new mathematical discoveries, which has led to the development of entirely new mathematical disciplines, such as statistics and game theory. Mathematicians also engage in pure mathematics, or mathematics for its own sake, without having any application in mind. There is no clear line separating pure and applied mathematics, and practical applications for what began as pure mathematics are often discovered.^[18]

History

Evolution

Main article: History of mathematics

Greek mathematicianPythagoras(c. 570 – c. 495 BC), commonly credited with discovering the Pythagorean theorem

The evolution of mathematics might be seen as an ever-increasing series of abstractions, or alternatively an expansion of subject matter. The first abstraction, which is shared by many animals,^[19] was probably that of numbers: the realization that a collection of two apples and a collection of two oranges (for example) have something in common, namely quantity of their members.

Mayan numerals

Evidenced by tallies found on bone, in addition to recognizing how to count physical objects, prehistoricpeoples may have also recognized how to count abstract quantities, like time – days, seasons, years.^[20]

More complex mathematics did not appear until around 3000 BC, when the Babylonians and Egyptians began using arithmetic, algebra and geometry for taxation and other financial calculations, for building and construction, and for astronomy.^[21] The earliest uses of mathematics were in trading, land measurement,painting and weaving patterns and the recording of time.

In Babylonian mathematics elementary arithmetic (addition, subtraction, multiplication and division) first appears in the archaeological record. Numeracy pre-dated writing and numeral systems have been many and diverse, with the first known written numerals created by Egyptians in Middle Kingdom texts such as the Rhind Mathematical Papyrus.^{[citation needed]}

Between 600 and 300 BC the Ancient Greeks began a systematic study of mathematics in its own right with Greek mathematics.^[22]

Mathematics has since been greatly extended, and there has been a fruitful interaction between mathematics and science, to the benefit of both. Mathematical discoveries continue to be made today. According to Mikhail B. Sevryuk, in the January 2006 issue of the Bulletin of the American Mathematical Society, "The number of papers and books included in the Mathematical Reviews database since 1940 (the first year of operation of MR) is now more than 1.9 million, and more than 75 thousand items are added to the database each year. The overwhelming majority of works in this ocean contain new mathematicaltheorems and their proofs."^[23]

Etymology

The word mathematics comes from the Greek μάθημα (máthēma), which, in the ancient Greek language, means "that which is learnt",^[24] "what one gets to know", hence also "study" and "science", and in modern Greek just "lesson". The word máthēma is derived from μανθάνω (manthano), while the modern Greek equivalent is μαθαίνω (mathaino), both of which mean "to learn". In Greece, the word for "mathematics" came to have the narrower and more technical meaning "mathematical study" even in Classical times.^[25] Its adjective is μαθηματικός (mathēmatikós), meaning "related to learning" or "studious", which likewise further came to mean "mathematical". In particular, μαθηματικὴ τέχνη(mathēmatikḗ tékhnē), Latin: ars mathematica, meant "the mathematical art".

In Latin, and in English until around 1700, the term mathematics more commonly meant "astrology" (or sometimes "astronomy") rather than "mathematics"; the meaning gradually changed to its present one from about 1500 to 1800. This has resulted in several mistranslations: a particularly notorious one is Saint Augustine's warning that Christians should beware of mathematici meaning astrologers, which is sometimes mistranslated as a condemnation of mathematicians.^[26]

The apparent plural form in English, like the French plural form les mathématiques (and the less commonly used singular derivative la mathématique), goes back to the Latin neuter plural mathematica (Cicero), based on the Greek plural τα μαθηματικά (ta mathēmatiká), used by Aristotle (384–322 BC), and meaning roughly "all things mathematical"; although it is plausible that English borrowed only the adjective mathematic(al) and formed the noun mathematics anew, after the pattern of physics and metaphysics, which were inherited from the Greek.^[27] In English, the noun mathematics takes singular verb forms. It is often shortened to maths or, in English-speaking North America, math.^[28]

Definitions of mathematics

Main article: Definitions of mathematics

Aristotle defined mathematics as "the science of quantity", and this definition prevailed until the 18th century.^[29] Starting in the 19th century, when the study of mathematics increased in rigor and began to address abstract topics such as group theory and projective geometry, which have no clear-cut relation to quantity and measurement, mathematicians and philosophers began to propose a variety of new definitions.^[30] Some of these definitions emphasize the deductive character of much of mathematics, some emphasize its abstractness, some emphasize certain topics within mathematics. Today, no consensus on the definition of mathematics prevails, even among professionals.^[7]There is not even consensus on whether mathematics is an art or a science.^[8] A great many professional mathematicians take no interest in a definition of mathematics, or consider it undefinable.^[7] Some just say, "Mathematics is what mathematicians do."^[7]

Three leading types of definition of mathematics are called logicist, intuitionist, and formalist, each reflecting a different philosophical school of thought.^[31] All have severe problems, none has widespread acceptance, and no reconciliation seems possible.^[31]

An early definition of mathematics in terms of logic was Benjamin Peirce's "the science that draws necessary conclusions" (1870).^[32] In the Principia Mathematica, Bertrand Russell and Alfred North Whitehead advanced the philosophical program known as logicism, and attempted to prove that all mathematical concepts, statements, and principles can be defined and proven entirely in terms of symbolic logic. A logicist definition of mathematics is Russell's "All Mathematics is Symbolic Logic" (1903).^[33]

Intuitionist definitions, developing from the philosophy of mathematician L.E.J. Brouwer, identify mathematics with certain mental phenomena. An example of an intuitionist definition is "Mathematics is the mental activity which consists in carrying out constructs one after the other."^[31] A peculiarity of intuitionism is that it rejects some mathematical ideas considered valid according to other definitions. In particular, while other philosophies of mathematics allow objects that can be proven to exist even though they cannot be constructed, intuitionism allows only mathematical objects that one can actually construct.

Formalist definitions identify mathematics with its symbols and the rules for operating on them. Haskell Curry defined mathematics simply as "the science of formal systems".^[34] Aformal system is a set of symbols, or tokens, and some rules telling how the tokens may be combined into formulas. In formal systems, the word axiom has a special meaning, different from the ordinary meaning of "a self-evident truth". In formal systems, an axiom is a combination of tokens that is included in a given formal system without needing to be derived using the rules of the system.

Inspiration, pure and applied mathematics, and aesthetics

Main article: Mathematical beauty

Isaac Newton (left) and Gottfried Wilhelm Leibniz (right), developers of infinitesimal calculus

Mathematics arises from many different kinds of problems. At first these were found in commerce, land measurement, architecture and later astronomy; today, all sciences suggest problems studied by mathematicians, and many problems arise within mathematics itself. For example, the physicist Richard Feynman invented the path integral formulation of quantum mechanics using a combination of mathematical reasoning and physical insight, and today's string theory, a still-developing scientific theory which attempts to unify the four fundamental forces of nature, continues to inspire new mathematics.^[35]

Some mathematics is relevant only in the area that inspired it, and is applied to solve further problems in that area. But often mathematics inspired by one area proves useful in many areas, and joins the general stock of mathematical concepts. A distinction is often made between pure mathematics and applied mathematics. However pure mathematics topics often turn out to have applications, e.g. number theory in cryptography. This remarkable fact that even the "purest" mathematics often turns out to have practical applications is whatEugene Wigner has called "the unreasonable effectiveness of mathematics".^[36] As in most areas of study, the explosion of knowledge in the scientific age has led to specialization: there are now hundreds of specialized areas in mathematics and the latest Mathematics Subject Classification runs to 46 pages.^[37] Several areas of applied mathematics have merged with related traditions outside of mathematics and become disciplines in their own right, including statistics, operations research, and computer science.

For those who are mathematically inclined, there is often a definite aesthetic aspect to much of mathematics. Many mathematicians talk about the elegance of mathematics, its intrinsic aesthetics and inner beauty. Simplicity and generality are valued. There is beauty in a simple and elegant proof, such as Euclid's proof that there are infinitely many prime numbers, and in an elegant numerical method that speeds calculation, such as the fast Fourier transform. G.H. Hardy in A Mathematician's Apology expressed the belief that these aesthetic considerations are, in themselves, sufficient to justify the study of pure mathematics. He identified criteria such as significance, unexpectedness, inevitability, and economy as factors that contribute to a mathematical aesthetic.^[38] Mathematicians often strive to find proofs that are particularly elegant, proofs from "The Book" of God according to Paul Erdős.^[39]^[40] The popularity of recreational mathematics is another sign of the pleasure many find in solving mathematical questions.

Notation, language, and rigor

Main article: Mathematical notation

Leonhard Euler, who created and popularized much of the mathematical notation used today

Most of the mathematical notation in use today was not invented until the 16th century.^[41] Before that, mathematics was written out in words, a painstaking process that limited mathematical discovery.^[42] Euler (1707–1783) was responsible for many of the notations in use today. Modern notation makes mathematics much easier for the professional, but beginners often find it daunting. It is extremely compressed: a few symbols contain a great deal of information. Like musical notation, modern mathematical notation has a strict syntax (which to a limited extent varies from author to author and from discipline to discipline) and encodes information that would be difficult to write in any other way.

Mathematical language can be difficult to understand for beginners. Words such as or and only have more precise meanings than in everyday speech. Moreover, words such as open and field have been given specialized mathematical meanings. Technical terms such as homeomorphismand integrable have precise meanings in mathematics. Additionally, shorthand phrases such as iff for "if and only if" belong to mathematical jargon. There is a reason for special notation and technical vocabulary: mathematics requires more precision than everyday speech. Mathematicians refer to this precision of language and logic as "rigor".

Mathematical proof is fundamentally a matter of rigor. Mathematicians want their theorems to follow from axioms by means of systematic reasoning. This is to avoid mistaken "theorems", based on fallible intuitions, of which many instances have occurred in the history of the subject.^[43] The level of rigor expected in mathematics has varied over time: the Greeks expected detailed arguments, but at the time of Isaac Newton the methods employed were less rigorous. Problems inherent in the definitions used by Newton would lead to a resurgence of careful analysis and formal proof in the 19th century. Misunderstanding the rigor is a cause for some of the common misconceptions of mathematics. Today, mathematicians continue to argue among themselves about computer-assisted proofs. Since large computations are hard to verify, such proofs may not be sufficiently rigorous.^[44]

Axioms in traditional thought were "self-evident truths", but that conception is problematic. At a formal level, an axiom is just a string of symbols, which has an intrinsic meaning only in the context of all derivable formulas of an axiomatic system. It was the goal of Hilbert's program to put all of mathematics on a firm axiomatic basis, but according toGödel's incompleteness theorem every (sufficiently powerful) axiomatic system has undecidable formulas; and so a final axiomatization of mathematics is impossible. Nonetheless mathematics is often imagined to be (as far as its formal content) nothing but set theory in some axiomatization, in the sense that every mathematical statement or proof could be cast into formulas within set theory.^[45]

Fields of mathematics

An abacus, a simple calculating tool used since ancient times

Mathematics can, broadly speaking, be subdivided into the study of quantity, structure, space, and change (i.e. arithmetic, algebra,geometry, and analysis). In addition to these main concerns, there are also subdivisions dedicated to exploring links from the heart of mathematics to other fields: to logic, to set theory (foundations), to the empirical mathematics of the various sciences (applied mathematics), and more recently to the rigorous study of uncertainty.

Foundations and philosophy

In order to clarify the foundations of mathematics, the fields of mathematical logic and set theory were developed. Mathematical logic includes the mathematical study of logic and the applications of formal logic to other areas of mathematics; set theory is the branch of mathematics that studies sets or collections of objects. Category theory, which deals in an abstract way with mathematical structures and relationships between them, is still in development. The phrase "crisis of foundations" describes the search for a rigorous foundation for mathematics that took place from approximately 1900 to 1930.^[46] Some disagreement about the foundations of mathematics continues to the present day. The crisis of foundations was stimulated by a number of controversies at the time, including the controversy over Cantor's set theory and the Brouwer–Hilbert controversy.

Mathematical logic is concerned with setting mathematics within a rigorous axiomatic framework, and studying the implications of such a framework. As such, it is home toGödel's incompleteness theorems which (informally) imply that any effective formal system that contains basic arithmetic, if sound (meaning that all theorems that can be proven are true), is necessarily incomplete (meaning that there are true theorems which cannot be proved in that system). Whatever finite collection of number-theoretical axioms is taken as a foundation, Gödel showed how to construct a formal statement that is a true number-theoretical fact, but which does not follow from those axioms. Therefore no formal system is a complete axiomatization of full number theory. Modern logic is divided into recursion theory, model theory, and proof theory, and is closely linked to theoretical computer science,^{[citation needed]} as well as to category theory.

Theoretical computer science includes computability theory, computational complexity theory, and information theory. Computability theory examines the limitations of various theoretical models of the computer, including the most well-known model – the Turing machine. Complexity theory is the study of tractability by computer; some problems, although theoretically solvable by computer, are so expensive in terms of time or space that solving them is likely to remain practically unfeasible, even with the rapid advancement of computer hardware. A famous problem is the "P = NP?" problem, one of the Millennium Prize Problems.^[47] Finally, information theory is concerned with the amount of data that can be stored on a given medium, and hence deals with concepts such as compression and entropy.


Mathematical logic	Set theory	Category theory	Theory of computation

Pure mathematics

Quantity

The study of quantity starts with numbers, first the familiar natural numbers and integers ("whole numbers") and arithmetical operations on them, which are characterized inarithmetic. The deeper properties of integers are studied in number theory, from which come such popular results as Fermat's Last Theorem. The twin prime conjecture andGoldbach's conjecture are two unsolved problems in number theory.

As the number system is further developed, the integers are recognized as a subset of the rational numbers ("fractions"). These, in turn, are contained within the real numbers, which are used to represent continuous quantities. Real numbers are generalized to complex numbers. These are the first steps of a hierarchy of numbers that goes on to include quaternions and octonions. Consideration of the natural numbers also leads to the transfinite numbers, which formalize the concept of "infinity". Another area of study is size, which leads to the cardinal numbers and then to another conception of infinity: the aleph numbers, which allow meaningful comparison of the size of infinitely large sets.


Natural numbers	Integers	Rational numbers	Real numbers	Complex numbers

Structure

Many mathematical objects, such as sets of numbers and functions, exhibit internal structure as a consequence of operations or relations that are defined on the set. Mathematics then studies properties of those sets that can be expressed in terms of that structure; for instance number theory studies properties of the set of integers that can be expressed in terms of arithmetic operations. Moreover, it frequently happens that different such structured sets (or structures) exhibit similar properties, which makes it possible, by a further step of abstraction, to state axioms for a class of structures, and then study at once the whole class of structures satisfying these axioms. Thus one can study groups,rings, fields and other abstract systems; together such studies (for structures defined by algebraic operations) constitute the domain of abstract algebra.

By its great generality, abstract algebra can often be applied to seemingly unrelated problems; for instance a number of ancient problems concerning compass and straightedge constructions were finally solved using Galois theory, which involves field theory and group theory. Another example of an algebraic theory is linear algebra, which is the general study of vector spaces, whose elements called vectors have both quantity and direction, and can be used to model (relations between) points in space. This is one example of the phenomenon that the originally unrelated areas of geometry and algebra have very strong interactions in modern mathematics. Combinatorics studies ways of enumerating the number of objects that fit a given structure.


Combinatorics	Number theory	Group theory	Graph theory	Order theory	Algebra

Space

The study of space originates with geometry – in particular, Euclidean geometry. Trigonometry is the branch of mathematics that deals with relationships between the sides and the angles of triangles and with the trigonometric functions; it combines space and numbers, and encompasses the well-known Pythagorean theorem. The modern study of space generalizes these ideas to include higher-dimensional geometry, non-Euclidean geometries (which play a central role in general relativity) and topology. Quantity and space both play a role in analytic geometry, differential geometry, and algebraic geometry. Convex and discrete geometry were developed to solve problems in number theoryand functional analysis but now are pursued with an eye on applications in optimization and computer science. Within differential geometry are the concepts of fiber bundles and calculus on manifolds, in particular, vector and tensor calculus. Within algebraic geometry is the description of geometric objects as solution sets of polynomial equations, combining the concepts of quantity and space, and also the study of topological groups, which combine structure and space. Lie groups are used to study space, structure, and change. Topology in all its many ramifications may have been the greatest growth area in 20th-century mathematics; it includes point-set topology, set-theoretic topology,algebraic topology and differential topology. In particular, instances of modern day topology are metrizability theory, axiomatic set theory, homotopy theory, and Morse theory. Topology also includes the now solved Poincaré conjecture, and the still unsolved areas of the Hodge conjecture. Other results in geometry and topology, including the four color theorem and Kepler conjecture, have been proved only with the help of computers.


Geometry	Trigonometry	Differential geometry	Topology	Fractal geometry	Measure theory

Change

Understanding and describing change is a common theme in the natural sciences, and calculus was developed as a powerful tool to investigate it. Functions arise here, as a central concept describing a changing quantity. The rigorous study of real numbers and functions of a real variable is known as real analysis, with complex analysis the equivalent field for the complex numbers. Functional analysis focuses attention on (typically infinite-dimensional) spaces of functions. One of many applications of functional analysis isquantum mechanics. Many problems lead naturally to relationships between a quantity and its rate of change, and these are studied as differential equations. Many phenomena in nature can be described by dynamical systems; chaos theory makes precise the ways in which many of these systems exhibit unpredictable yet still deterministic behavior.


Calculus	Vector calculus	Differential equations	Dynamical systems	Chaos theory	Complex analysis

Applied mathematics

Applied mathematics concerns itself with mathematical methods that are typically used in science, engineering, business, and industry. Thus, "applied mathematics" is amathematical science with specialized knowledge. The term applied mathematics also describes the professional specialty in which mathematicians work on practical problems; as a profession focused on practical problems, applied mathematics focuses on the "formulation, study, and use of mathematical models" in science, engineering, and other areas of mathematical practice.

In the past, practical applications have motivated the development of mathematical theories, which then became the subject of study in pure mathematics, where mathematics is developed primarily for its own sake. Thus, the activity of applied mathematics is vitally connected with research in pure mathematics.

Statistics and other decision sciences

Applied mathematics has significant overlap with the discipline of statistics, whose theory is formulated mathematically, especially with probability theory. Statisticians (working as part of a research project) "create data that makes sense" with random sampling and with randomized experiments;^[48] the design of a statistical sample or experiment specifies the analysis of the data (before the data be available). When reconsidering data from experiments and samples or when analyzing data from observational studies, statisticians "make sense of the data" using the art of modelling and the theory of inference – with model selection and estimation; the estimated models and consequential predictions should be tested on new data.^[49]

Statistical theory studies decision problems such as minimizing the risk (expected loss) of a statistical action, such as using a procedure in, for example, parameter estimation,hypothesis testing, and selecting the best. In these traditional areas of mathematical statistics, a statistical-decision problem is formulated by minimizing an objective function, like expected loss or cost, under specific constraints: For example, designing a survey often involves minimizing the cost of estimating a population mean with a given level of confidence.^[50] Because of its use of optimization, the mathematical theory of statistics shares concerns with other decision sciences, such as operations research, control theory, and mathematical economics.^[51]

Computational mathematics

Computational mathematics proposes and studies methods for solving mathematical problems that are typically too large for human numerical capacity. Numerical analysisstudies methods for problems in analysis using functional analysis and approximation theory; numerical analysis includes the study of approximation and discretization broadly with special concern for rounding errors. Numerical analysis and, more broadly, scientific computing also study non-analytic topics of mathematical science, especially algorithmic matrix and graph theory. Other areas of computational mathematics include computer algebra and symbolic computation.


Mathematical physics	Fluid dynamics	Numerical analysis	Optimization	Probability theory	Statistics	Cryptography

Mathematical finance	Game theory	Mathematical biology	Mathematical chemistry	Mathematical economics	Control theory

Mathematical awards

Arguably the most prestigious award in mathematics is the Fields Medal,^[52]^[53] established in 1936 and now awarded every four years. The Fields Medal is often considered a mathematical equivalent to the Nobel Prize.

The Wolf Prize in Mathematics, instituted in 1978, recognizes lifetime achievement, and another major international award, the Abel Prize, was introduced in 2003. The Chern Medal was introduced in 2010 to recognize lifetime achievement. These accolades are awarded in recognition of a particular body of work, which may be innovational, or provide a solution to an outstanding problem in an established field.

A famous list of 23 open problems, called "Hilbert's problems", was compiled in 1900 by German mathematician David Hilbert. This list achieved great celebrity among mathematicians, and at least nine of the problems have now been solved. A new list of seven important problems, titled the "Millennium Prize Problems", was published in 2000. A solution to each of these problems carries a $1 million reward, and only one (the Riemann hypothesis) is duplicated in Hilbert's problems.

Mathematics as science

Carl Friedrich Gauss, known as the "prince of mathematicians"^[54]

Gauss referred to mathematics as "the Queen of the Sciences".^[13] In the original Latin Regina Scientiarum, as well as in German Königin der Wissenschaften, the word corresponding to science means a "field of knowledge", and this was the original meaning of "science" in English, also; mathematics is in this sense a field of knowledge. The specialization restricting the meaning of "science" to natural science follows the rise ofBaconian science, which contrasted "natural science" to scholasticism, the Aristotelean method of inquiring from first principles. The role of empirical experimentation and observation is negligible in mathematics, compared to natural sciences such as psychology, biology, or physics.Albert Einstein stated that "as far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."^[16] More recently, Marcus du Sautoy has called mathematics "the Queen of Science ... the main driving force behind scientific discovery".^[55]

Many philosophers believe that mathematics is not experimentally falsifiable, and thus not a science according to the definition of Karl Popper.^[56]However, in the 1930s Gödel's incompleteness theorems convinced many mathematicians^[who?] that mathematics cannot be reduced to logic alone, and Karl Popper concluded that "most mathematical theories are, like those of physics and biology, hypothetico-deductive: pure mathematics therefore turns out to be much closer to the natural sciences whose hypotheses are conjectures, than it seemed even recently."^[57]Other thinkers, notably Imre Lakatos, have applied a version of falsificationism to mathematics itself.

An alternative view is that certain scientific fields (such as theoretical physics) are mathematics with axioms that are intended to correspond to reality. The theoretical physicist J.M. Ziman proposed that science is public knowledge, and thus includes mathematics.^[58] Mathematics shares much in common with many fields in the physical sciences, notably the exploration of the logical consequences of assumptions. Intuition and experimentation also play a role in the formulation of conjectures in both mathematics and the (other) sciences. Experimental mathematics continues to grow in importance within mathematics, and computation and simulation are playing an increasing role in both the sciences and mathematics.

The opinions of mathematicians on this matter are varied. Many mathematicians^[who?] feel that to call their area a science is to downplay the importance of its aesthetic side, and its history in the traditional seven liberal arts; others^[who?] feel that to ignore its connection to the sciences is to turn a blind eye to the fact that the interface between mathematics and its applications in science and engineering has driven much development in mathematics. One way this difference of viewpoint plays out is in the philosophical debate as to whether mathematics is created (as in art) or discovered (as in science). It is common to see universities divided into sections that include a division of Science and Mathematics, indicating that the fields are seen as being allied but that they do not coincide. In practice, mathematicians are typically grouped with scientists at the gross level but separated at

The History of Ceiling fan

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Ceiling fan

A modern ceiling fan

A ceiling fan is a mechanical fan, usually electrically powered, suspended from the ceiling of a room, that uses hub-mountedrotating paddles to circulate air.

Casablanca Fan Co. ceiling fan from the early 1980s.

A ceiling fan rotates much more slowly than an electric desk fan; it cools people effectively by introducing slow movement into the otherwise still, hot air of a room, inducing evaporative cooling. Fans never actually cool air, unlike air-conditioning equipment, but use significantly less power (cooling air is thermodynamically expensive). Conversely, a ceiling fan can also be used to reduce the stratification of warm air in a room by forcing it down to affect both occupants' sensations and thermostat readings, thereby improving climate control energy efficiency.

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History

The first ceiling fans appeared in the early 1860s and 1870s, in the United States. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. These systems could accommodate several fan units, and so became popular in stores, restaurants, and offices. Some of these systems still survive today, and can be seen in parts of the southern United States where they originally proved useful. The electrically powered ceiling fan was invented in 1882 by Philip Diehl; he had engineered the electric motor used in the first electrically powered Singer sewing machines, and in 1882 adapted that motor for use in a ceiling-mounted fan. Each fan had its own self-contained motor unit, with no need for belt drive.^[1] He was almost immediately up against fierce competition due to the commercial success of the ceiling fan. He continued to make improvements to his invention; by creating a light kit fitted to the ceiling fan to combine both functions in one unit. By World War I most ceiling fans were made with four blades instead of the original two, which made fans quieter and allowed them to circulate more air.

By the 1920s ceiling fans had become commonplace in the United States, and had started to take hold internationally. From the Great Depression of the 1930s until the introduction of electric air conditioning in the 1950s ceiling fans slowly faded out of vogue in the U.S.,^[1] almost falling into total disuse in the U.S.; those which remained were considered items of nostalgia.

Meanwhile, they had become very popular in other countries, particularly those with hot climates such as India but without the infrastructure or financial resources for high-energy-consuming and complex freon induced air conditioning equipment. In 1973, Texas entrepreneur H.W. (Hub) Markwardt began importing highly efficient ceiling fans to theUnited States that were manufactured in India by Crompton-Greaves, Ltd. Crompton-Greaves had been manufacturing ceiling fans since 1937 through a joint venture formed by Greaves Cotton of India and Crompton-Parkinson of England, and had perfected the world's most energy efficient ceiling fans thanks to its patented 20 pole induction motor with highly efficient heat-dissipating cast aluminum rotor shell. These Indian manufactured ceiling fans caught on slowly at first, but Markwardt's Encon Industries branded ceiling fans (ENergy CONservation) eventually found great success during the energy crisis of the late 1970s and early 1980s, since they consumed far less energy (under 70 watts of electricity) than the antiquated shaded pole motors used in most other American made fans, and far more efficient than using expensive air conditioning units.

Due to this renewed commercial success using ceiling fans effectively as an energy conservation application, many American manufacturers also started to produce, or significantly increase production of, ceiling fans. In addition to the imported Encon ceiling fans, the Casablanca Fan Company was founded in 1977. Other American manufacturers of the time included the Hunter Fan Co. (which was then a division of Robbins & Myers, Inc), FASCO (F. A. Smith Co.), Emerson Electric, and Lasko; the latter two were often branded as Sears-Roebuck.

Through the 1980s and 1990s, ceiling fans remained popular in the United States. Many small American importers, most of them rather short-lived, started importing ceiling fans. Throughout the 1980s the balance of sales between American-made ceiling fans and those imported from manufacturers in India, Taiwan, Hong Kong and eventually Chinachanged dramatically with imported fans taking the lion's share of the market by the late 1980s. Even the most basic U.S-made fans sold at $200 to $500, while the most expensive imported fans rarely exceeded $150.

Since 2000 important inroads have been made by companies offering higher price ceiling fans with more decorative value. In 2001, Washington Post writer Patricia Dane Rogers^[2] wrote, “Like so many other mundane household objects, these old standbys are going high-style and high-tech.” Newer companies such as Monte Carlo, Ellington, Quorum, Craftmade, Minka, Fanimation, The Modern Fan Co. and Big-Ass Fans brought well-built fans with distinctive design to the market.

Uses

Unlike air conditioners, fans only move air—they do not directly change its temperature. Therefore ceiling fans that have a mechanism for reversing the direction in which the blades rotate (most commonly an electrical switch on the side of the unit) can help in both heating and cooling.

Some ceiling fans have adjustable blade pitch instead of reversible motor. In this case, the blade should be pitched to the right (or left if the motor spins clockwise) for downdraft, and left (or right if the motor spins clockwise) for updraft. Hunter Hotel Original is one example.

In summer, the fan's direction of rotation should be set so that air is blown downward (Usually counter-clockwise from beneath). The blades should lead with the upturned side as they spin. The breeze created by a ceiling fan speeds the evaporation of perspiration on human skin, which makes the body's natural cooling mechanism much more efficient. Since the fan works directly on the body, rather than by changing the temperature of the air, during the summer it is a waste of electricity to leave a ceiling fan on when no one is in a room.^[3]

In winter, ceiling fans should be set to turn the opposite direction (usually clockwise; the blades should spin with the downward turned side leading) and on a low speed (or the lowest speed the fan is able to circulate the air down to the floor). Air naturally stratifies—that is, warmer air rises to the ceiling while cooler air sinks. Unfortunately, this means it is colder on or near the floor where human beings spend most of their time. A ceiling fan, with its direction of rotation set so that air is drawn upward, pulls up the colder air below, forcing the warmer air nearer the ceiling to move down to take its place, without blowing a stream of air directly at the occupants of the room. This action works to even out the temperature in the room, making it cooler nearer the ceiling, but warmer nearer the floor. Thus the thermostat in the area can be set a few degrees lower to save energy, while maintaining the same level of comfort. It is important to run the fan at a low speed (or a lowest speed the fan is able to circulate the air down to the floor) to minimize the wind chill effect described above.

An additional use of ceiling fans is coupling them with an air conditioning unit. Through-the-wall/through-the-window air conditioning units typically found in rented properties in North America usually have both the tasks of cooling the air inside the room and circulating it. Provided the ceiling fan is properly sized for the room in which it is operating, its efficiency of moving air far exceeds that of an air conditioning unit, therefore, for peak efficiency, the air conditioner should be set to a low fan setting and the ceiling fan should be used to circulate the air.

Exception

There is an exception to the standard rule of blowing air down in the summer and pulling it up in the winter. When a ceiling fan is mounted in a room with very high ceilings (two stories/levels high or higher),or at the head of a tall set of stairs, the mode of operation is reversed. In this scenario the fan is mounted so high up that there is no significant "wind chill effect". The purpose then becomes to move hot air down in the winter and pull cold air up in the summer.^[4]

Parts of a ceiling fan

The key components of a ceiling fan are the following:

An electric motor (see Types of ceiling fans below for descriptions)
Blades (known as paddles or wings) usually made from wood, plywood, iron, aluminum or plastic
Metal arms, called blade irons (alternately blade brackets, blade arms, blade holders, or flanges), which hold the blades and connect them to the motor.
Flywheel, a metal or tough rubber double-torus which is attached to the motor shaft, and to which the blade irons may be attached. The flywheel inner ring is locked to the shaft by a lock-screw, and the blade irons to the outer ring by bolts that feed into tapped metal inserts. Older flywheels may become brittle and break, a common cause of fan failure. Replacing the flywheel requires disconnecting wiring and removing the switch housing to gain access to the shaft lock-screw.
Rotor, alternative to blade irons. First patented by industrial designer Ron Rezek in 1991, the one-piece die cast rotor receives and secures the blades and bolts right to the motor, eliminating most balance problems and minimizing exposed fasteners.
A mechanism for mounting the fan to the ceiling such as:
- ball-and-socket system. With this system, there is a metal or plastic hemisphere mounted on the end of the downrod; this hemisphere rests in a ceiling-mounted metal bracket and allows the fan to move freely (which is very useful on vaulted ceilings). Some companies have come up with slight modifications of this design.
- J-hook (Claw hook) system. a type of mounting system where the ceiling fan hangs on a metal hook, attached to the ceiling. A rubber grommet is used to keep the fan in place and helps avoid vibration on the ceiling.
- Some fans can be mounted using a low-ceiling adapter, a special kit which must be purchased from the fan's manufacturer. This eliminates the need for a downrod, and is therefore useful in rooms with low ceiling clearance.
- In recent years, it has become increasingly common for a ball-and-socket fan to be designed such that the canopy (ceiling cover piece) can optionally be screwed directly into the top of the motor housing; then the whole fan can be secured directly onto the ceiling mounting bracket. This is known as a "close-to-ceiling" mount.

Other components, which vary by model and style, can include:

A downrod, a metal pipe used to suspend the fan from the ceiling. Downrods come in many lengths and widths, depending on the fan type.
A decorative encasement for the motor (known as the "motor housing").
A switch housing (also known as a "switch cup"), a metal cylinder mounted below and in the center of the fan's motor. The switch housing is used to conceal and protect various components, which can include wires, capacitors, and switches; on fans that require oiling, it often conceals the oil reservoir which lubricates the bearings. The switch housing also makes for a convenient place to mount a light kit.
Blade badges, decorative adornments attached to the visible underside of the blades for the purpose of concealing the screws used to attach the blades to the blade irons.
Assorted switches used for turning the fan on and off, adjusting the speed at which the blades rotate, changing the direction in which the blades rotate, and operating any lamps that may be present.
Lamps
- Uplights, which are installed on top of the fan's motor housing and project light up onto the ceiling, for aesthetic reasons (to "create ambiance")
- Downlights, often referred to as a "light kit", which add ambient light to a room and can be used to replace any ceiling-mounted lamps that were displaced by the installation of a ceiling fan
- Decorative light bulbs mounted inside the motor housing—in this type of setup, the motor housing often has glass panel sections which allow light to shine though.

Configurations

Commercial or industrial ceiling fans are usually used in offices, factories or industries. Commercial ceiling fans are designed to be more cost effective and more energy efficient then other cooling alternatives. The industrial or commercial ceiling fans usually use three blades and operate with a high-speed motor. Some can be found with more than 3 blades though. These energy efficient ceiling fans usually push massive amounts of air compared to other ceiling fan types. In the 1980s, it was common to find metal-bladed industrial ceiling fans in American households, while industrial fans in household applications are still commonplace today in Middle-Eastern households.
A hugger or low profile ceiling fan is usually installed on a low ceiling. They can also be used in rooms with vaulted ceilings when installed on the joist (picture on the right shows an example). In cold climates, a ceiling fan may disperse heat to warm up the room as well by dispersing downwards the warm air that rises to the ceiling surface. Though the ceiling fan cannot lower room temperatures, when used in tandem with a room air-conditioner it may be able to disperse the cool air all around the room.
Outdoor ceiling fans are ceiling fans designed for outdoor purposes, they are usually water resistant and made of materials that do not get affected by outside temperatures, weather or humidity.
Energy Star ceiling fans are manufactured under the Energy Star label. Usually energy star fans hold the distinction of being more energy efficient (50%), have lower price tags, and save a lot of money on energy savings.

Operating a ceiling fan

This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (September 2011)

A Hunter-branded "Eclipse", which is a basic modern ceiling fan with standard pull-chain controls for the fan motor and light kit

The way in which a fan is operated depends on its manufacturer, style, and the era in which it was made. Operating methods include:

Pull-chain/pull-cord control. This style of fan is equipped with a metal-bead chain or cloth cord which, when pulled, cycles the fan through the operational speed(s) and then back to off. These fans usually have three speeds.
Variable-speed control. During the 1970s and 1980s, fans were often produced with a variable-speed control. This was a dial mounted on the fan which, when turned in either direction, continuously varied the speed at which the blades rotated—similar to a dimmer switch for a light fixture. A few fans substituted a rotary click-type switch for the infinite-speed dial, providing a set number of speeds (usually ranging from five to ten).
- Different fan manufacturers used the variable-speed control in different ways:
  - The variable-speed dial controlling the fan entirely; to turn the fan on, the user turns the knob until it clicks out of the "off" position, and can then choose the fan's speed.
  - A pull-chain present along with the variable-speed control; the dial can be set in one place and left there, with the pull-chain serving only to turn the fan on and off. Many of these fans have an option to wire the light kit to this pull-chain in order to control both the fan and the light with one chain. Using this method, the user can have either the fan or light on individually, both on, or both off.
  - "Vari-Lo": A pull-chain and variable-speed control are present. Such a fan has two speeds controlled by a pull-chain: high (full power, independent of the position of the variable-speed control), and "Vari-Lo" (speed determined by the position of the variable-speed control).
Wall-mounted control. Some fans have their control(s) mounted the wall instead of on the fans themselves; such controls are usually proprietary and/or specialized switches.
- Digital control. With this style of control, all of the fan's functions—on/off status, speed, direction of rotation, and any attached light fixtures—are controlled by a computerized wall control, which typically does not require any special wiring. Instead, it uses the normal house wiring to send coded electrical pulses to the fan, which decodes and acts on them using a built-in set of electronics. This style of control typically has anywhere from three to six speeds.

Old-style and new-style chokes

- Choke. This style of switch takes varying physical forms. The wall control, which contains a motor speed regulator of some sort, determines how much power is delivered to the fan and therefore how fast it spins. Older such controls employed a choke—a large iron-cored coil—as their regulator; these controls were typically large, boxy, and surface-mounted on the wall. They had anywhere from four to eight speeds, typically four or five. Newer versions of this type of control do not use a choke as such, but much smaller capacitors or electronic circuitry; the switch is typically mounted in a standard in-wall gang box.
- Solid state variable speed control. These controls, commonly used on industrial fans, can control more than one (up to 15) fans with one switch. 2.5 to 6 amp controls can typically be installed in "gangs" with other solid-state controls or standard light switches or wiring devices, while 8 to 15 amp controls have a large heat sink and cannot be "ganged" with other devices.
Wireless remote control. In recent years, remote controls have dropped in price to become cost-effective for controlling ceiling fans. They may be supplied with fans, or fitted to an existing fan. The hand-held remote transmits radio frequency or infrared control signals to a receiver unit installed in the fan.

Types of ceiling fans

Many styles of ceiling fans have been developed over the years in response to several different factors such as growing energy-consumption consciousness and changes in decorating styles. The advent and evolution of electronic technology has also played a major role in ceiling fan development. Following is a list of major ceiling fan styles and their defining characteristics:

A cast-iron ceiling fan made by Hunter, dating from the early 1980s. This model is called the "Original".

Cast-iron ceiling fans. Cast-iron ceiling fans account for almost all ceiling fans made from their invention in 1882 through the 1950s. A cast-iron housing encases a very heavy-duty oil-bath motor, usually of the shaded-pole variety. These fans must be oiled periodically, usually once or twice per year, since they use an oil-bath system for lubrication. Because these fans are so sturdily built, and due to their utter lack of electronic components, it is not uncommon to see cast-iron fans aged eighty years or more running strong and still in use today.

A Dual-blade Ceiling fan in India

The Hunter 'Original' (manufactured by the Hunter Fan Co., formerly a division of Robbins & Myers, Inc.) is an example of a cast-iron ceiling fan. It has enjoyed the longest production run of any fan in history, dating from 1906 to the present (it is still being manufactured as the "Classic Original", with several spin-off models). The Original employed a shaded-pole motor from its inception until the late 1980s, at which point it was changed to a permanent split-capacitor motor. Though the fan's physical appearance remained unchanged, the motor was further downgraded in 2002 when production was shipped to Taiwan; the motor, though still oil-lubricated, was switched to a "skeletal" design, as discussed below.

A close-up of the dropped flywheel on a FASCO ceiling fan

The Emerson "Heat Fan", one of the first fans to use a stack motor

20 pole Induction "Pancake" motor ceiling fans, with highly efficient cast aluminum housings, were invented in 1957 by Crompton-Greaves, Ltd of India and were first imported into the United States in 1973 by Encon Industries. This Crompton-Greaves motor was developed through a joint venture with Crompton-Parkinson of England and took 20 years to perfect. It is considered the most energy efficient motor ever manufactured for ceiling fans since it consumes less energy than a household incandescent light bulb.
Stack-motor ceiling fans. In the late 1970s, due to rising energy costs prompted by the energy crisis, Emerson invented a new style of electric motor designed specifically for ceiling fans, the "stack" motor. Along with Encon's cast aluminum 20 pole motor, this powerful, energy-efficient motor aided in the comeback of ceiling fans in America, since it was far less expensive to operate than air conditioning. With this design (which consists of a basic stator and squirrel-cage rotor), the fan's blades mount to a central hub, known as aflywheel. The flywheel can be made of either metal or reinforced rubber, and can be mounted either flush with the fan's motor housing (concealed) or prominently below the fan's motor housing (known as a "dropped flywheel"). Many manufacturers used and/or developed their own stack motors, including (but not limited to) Casablanca, Emerson, FASCO, Hunter, and NuTone. Some manufacturers trademarked their personal incarnation of this motor: for example, Emerson came out with the "K-55" and "K-63" motors, Fanimation with the "FDK-2100", and Casablanca with the "XLP-2000". One of the earliest stack-motor fans was the Emerson "Heat Fan", aka the "Universal Series" or "Blender Fan" (informally), a utilitarian fan with a dropped metal flywheel and blades made of fiberglass or plastic. This fan was produced from 1976 through 1983 and, while targeted at commercial settings, also found great success in residential settings. Another stack-motor fan; one without the dropped flywheel; is the Casablanca "Delta" (3-speed model as compared to the "Zephyr" which is a variable-speed model) pictured at the beginning of this article. While this motor is not nearly as widely used as in the 1970s and 1980s, it can still be found in certain high-end Casablanca and Emerson fans.

One disadvantage of this type of fan is that the flywheel, if it is made from rubber, will dry out and crack over time and eventually break; this is usually not dangerous, but it renders the fan inoperable until the flywheel is replaced.

Direct-drive ceiling fans employ a motor with a stationary inner core with a shell, made of cast-iron, cast-aluminum, or (most commonly) stamped steel, that revolves around it (commonly called a "spinner" motor); the blades attach to this shell. Direct-drive motors are the least expensive motors to produce, and on the whole are the most prone to failure and noise generation.^[1] While the very first motors of this type (first used in the 1960s) were relatively heavy-duty, the quality of these motors has dropped significantly in recent years. This type of motor has become the standard for today's fans; it has been (and is) used in most Hampton Bay and Harbor Breeze ceiling fans, and has become commonly used by all other brands.
Spinner fans employ a direct-drive motor and do not have a stationary decorative cover (motor housing). This accounts for most industrial-style fans (though such fans sometimes have more moderate-quality motors), and some inexpensive residential-style fans (particularly those made overseas^[where?]).
Spinner-motor fans, sometimes incorrectly referred to as "spinners", employ a direct-drive (spinner) motor and do have a stationary decorative cover (motor housing). "Spinner-motor" fans account for nearly all fans manufactured from the late 1980s to the present.

A spinner fan

Skeletal motors, which are a high-quality subset of direct-drive motors, can be found on some higher-quality fans. Examples of skeletal motors include Hunter's "AirMax" motor, Casablanca's "XTR200" motor, and the motors made by Lasko for use in their ceiling fans. Skeletal motors differ from regular direct-drive motors in that:
- They have an open ("skeletal") design, which allows for far better ventilation and therefore a longer lifespan. This is in comparison to a regular direct-drive motor's design, in which the motor's inner workings are completely enclosed within a tight metal shell which may or may not have openings for ventilation; when openings are present, they are almost always small to the point of being inadequate.
- They are larger than regular direct-drive motors and, as a result, are more powerful and less prone to burning out.
Friction-drive ceiling fans. This short-lived type of ceiling fan was attempted by companies such as Emerson and NuTone in the late 1970s with little success. Its advantage was its tremendously low power consumption, but the fans were unreliable and very noisy, in addition to being grievously underpowered. Friction-drive ceiling fans employ a low-torque motor that is mounted transversely in relation to the flywheel. A rubber wheel mounted on the end of the motor's shaft drove a hub (via contact friction, hence the name) which, in turn, drove the flywheel. It was a system based on the fact that a low-torque motor spinning quickly can drive a large, heavy device at a slow speed without great energy consumption (see Gear ratio).
Gear-drive ceiling fans. These were similar to (and even less common than) the friction drive models; however, instead of a rubber wheel on the motor shaft using friction to turn the flywheel, a gear on the end of the motor shaft meshed with gear teeth formed into the flywheel, thus rotating it. The company "Panama" made gear driven ceiling fans.
Internal belt-drive ceiling fans. These were also similar in design to gear-drive and friction-drive fans; however, instead of a rubber friction wheel or toothed gear, a small rubber belt linked the motor to the flywheel. The most notable internal belt-drive ceiling fan was a model sold by Toastmaster.

Three fans driven by a single motor and belts

Belt-driven ceiling fans. As stated earlier in this article, the first ceiling fans used a water-powered system of belts to turn the blades of fan units (which consisted of nothing more than blades mounted on a flywheel). For period-themed decor, a few companies (notably Fanimation) have created reproduction belt-drive fan systems. The reproduction systems feature an electric motor as the driving force, in place of the water-powered motor.
Punkah style ceiling fans. These fans are based on the earliest form of a fan, that was developed in India which was originally cut from an Indian palmyra leaf. A punkah fan moves slowly in a pendular manner with a rather large blade and is nowadays electrically powered using a belt-driven system. In comparison to a rotating fan it creates a gentle breeze rather than an airflow.

Safety concerns with installation

A typical ceiling fan weighs between 15 and 50 pounds when fully assembled. While many junction boxes can support that weight while the fan is hanging still, a fan in operation exerts many additional stresses—notably torsion—on the object from which it is hung; this can cause an improper junction box to fail. For this reason, in the United States the National Electric Code (document NFPA 70, Article 314) states that ceiling fans must be supported by an electrical junction box listed for that use. It is a common mistake for homeowners to replace a light fixture with a ceiling fan without upgrading to a proper junction box.

Low-hanging fans/danger to limbs

Another concern with installing a ceiling fan relates to the height of the blades relative to the floor. Building codes throughout the United States prohibit residential ceiling fans from being mounted with the blades closer than seven feet from the floor; this often proves, however, to not be high enough. If a person fully extends his or her arms into the air—as sometimes happens during normal tasks such as stretching, changing bedsheets, or recreation—it is possible for the blades to strike their hands, potentially causing injury. Also, if one is wearing a tall hat, carrying a ladder, long wooden board, pipe, or some other long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades, which can be dangerous and can cause damage to the fan regardless.

MythBusters: "Killer Ceiling Fan"

In 2004, MythBusters tested the idea that a ceiling fan is capable of decapitation if an individual was to stick his or her neck into a running fan. Two versions of the myth were tested, with the first being the "jumping kid", involving a kid jumping up and down on a bed, jumping too high and entering the fan from below and the second being the "lover's leap", involving a husband dressed in a costume, leaping towards his wife in bed and entering the fan side-on. Kari Byron, Tory Belleci and Scottie Chapman took the lead on the investigation, though original MythBusters Jamie Hyneman and Adam Savage also assisted.

First, Kari and Scottie purchased a regular household fan and also an industrial fan, which has metal blades as opposed to wood and a more powerful motor. They and Tory then fashioned their human analogs - ballistic gel busts of Adam with actual human craniums, pig spines to approximate human spines, and latex arteries filled with fake blood - and then constructed rigs for both scenarios.

They busted the myth in both scenarios with both household and industrial fans, as tests proved that residential ceiling fans are, apparently by design, largely incapable of causing more than minor injury, having low-torque motors that stop quickly when blocked and blades composed of light materials that tend to break easily if impacted at speed (the household fan test of the "lover's leap" scenario actually broke the fan blades.) They did find that industrial fans, with their steel blades and higher speeds, proved capable of causing injury and laceration - building codes require industrial fans to be mounted with blades 10 feet above the floor, and the industrial fan test of the "lover's leap" scenario produced a lethal injury where the fan sliced through the jugular and into the vertebrae - but still lost energy rapidly once blocked and were unable to decapitate the test dummy. As a finale, Scottie, Tory and Kari created an even more dangerous fan with a lawn mower engine as the fan motor and razor sharp blades made from sheet metal in an attempt to duplicate the result, and even it was unable to achieve decapitation, but it caused lethal and horrifying injuries that compelled Adam to put it into the "MythBusters Hall of Fame."^[5]

Wobbling

Wobbling is caused by the weight of fan blades being out of balance with each other. This can happen due to a variety of factors, including blades being warped, blade irons being bent, blades or blade irons not being screwed on straight, or blades being different weights or shapes or sizes (minute differences matter). Also, if all the blades do not exert an equal force on the air (because they have different angles, for instance), the vertical reaction forces can cause wobbling. Wobbling is not affected by the way in which the fan is mounted or the mounting surface.

Contrary to popular misconception, wobbling will not cause a ceiling fan to fall.^[6] Ceiling fans are secured by clevis pins locked with either split pins or R-clips, so wobbling won't have an effect on the fan's security. To date, there are no reports of a fan wobbling itself off the ceiling and falling. However, a severe wobble can cause light fixture shades or covers to gradually loosen over time and potentially fall, posing a risk of injury to anyone under the fan, and also from any resulting broken glass. It is also worth mentioning that when the MythBusters were designing a fan with the goal of chopping off someone's head, Scottie used an edge finder to find the exact center of their blades with the aim of eliminating potentially very dangerous wobbling of their steel blades. It is important that, when installing the fan, the installer closely follows the manufacturer's instructions with regard to using proper mounting screws. It is also important that all screws (especially the set screws which hold twist-on downrods in place) be tight, and any ceiling fan light fixtures are properly assembled with their shades and covers securely attached.

Think about it!

2014-12-09T21:49:00.001-08:00

The Master's Degree History

2014-11-30T07:34:00.001-08:00

Master's degree

A master's degree is an academic degree granted to individuals who have undergone study demonstrating a mastery or high-order overview of a specific field of study or area of professional practice.^[1] Within the area studied, graduates are posited to possess advanced knowledge of a specialized body of theoretical and applied topics; high order skills in analysis, critical evaluation or professional application; and the ability to solve complex problems and think rigorously and independently. The degree is awarded upon graduation from a university.^[1]^{[dead link]}

Titles[edit]

The two most common titles of master's degrees are the Master of Arts (M.A.) and Master of Science (M.S., MSc, M.Si., or M.C.A.); these may be course-based, research-based, or a mixture of the two. Some universities use the Latin degree names; because of the flexibility of syntax in Latin, the Master of Arts and Master of Science may be known asmagister artium or artium magister and magister scientiae or scientiae magister, respectively. Harvard University, University of Chicago, and MIT, for example, use A.M. and S.M. for their master's degrees. More commonly, Master of Science often is abbreviated MS or M.S. in the United States, and MSc or M.Sc. in Commonwealth nations and Europe.

Other master's degrees are more specifically named ("tagged degrees"), including, for example, the Master of Business Administration (MBA), the Master of Business Engineering (MBE), Master in European Business (MEB), Master of Counselling (MC), Master of Library Science (MLS), Master of Public Administration (MPA), Master of Public Policy (MPP), Master of Laws (LL.M.), Master of Music (M.M. or M.Mus.), Master of Information (MI), Master of Fine Arts (M.F.A.).

Some are further general, for example the M.Phil., Master of Arts in Liberal Studies (MALS, MLA/ALM, and MLS), and the Master of Studies (Advanced Study / Advanced Studies).

See List of master's degrees.

Types[edit]

Post-graduate master's degree (MA, MS, MEd, MSc, MEB, MDes, MNCM, MSN, MSW, MPA, MPC, MPP, MPH, MC, MCA, MCouns, MLA, MLIS, MDiv, ALM, MiM, MBA, MBA Tech, MBE, MCom, MBus, MI, PSM and other subject specific master's degrees) is designed for anyone who holds a bachelor's degree.
Post-graduate research master's degree (MRes, MARes, MScRes, MPhil) - the Master by Research is designed for those who hold a bachelor's degree with a significant research component and/or have several publications. It is designed for those wishing to pursue higher research.
Executive master's degree (EMBA, EMS) is a master's degree designed specially for executive professionals. Admission, graduation requirements, and structure of executive master's degrees differ from that of the regular full-time program.^{[citation needed]}
Integrated master's degree (MEng, MMath, MPhys, MPsych, MSci, MChem, MBiol, MGeol etc.) is an undergraduate degree combined with an extra master's year. The first three years of study are often the same as a bachelor's degree, followed by an additional year of study at a master's degree level. The degree is only conferred at the end of study as a full master's - an intermediate bachelor's degree is not awarded. Integrated master's are most common in scientific disciplines.

Structure[edit]

Further information: Master's degree in North America, Master's degree in Europe and Master's degree non-Euroamerican

There are a range of pathways to the degree, with entry based on evidence of a capacity to undertake higher degree studies in the proposed field. A dissertation may or may not be required, depending on the program. In general, the structure and duration of a program of study leading to a master's degree will differ by country and by university.

Duration[edit]

In some systems, such as those of the United States and Japan, a master's degree is a strictly postgraduate academic degree. Particularly in the U.S., in some fields/programs, work on a doctorate begins immediately after the bachelor's degree, but the master's may be earned along the way as a 'master's degree "en route"', following successful completion of coursework and certain examinations. Master's programs are thus one to six years in duration, with two to three years being a common length of time to complete.

Under the Angloamerican systems many master's degrees are differentiated either as 'master (thesis)' or as 'master (non-thesis)' programs. Regardless of a de jure minimum period of a master degree program in the same discipline, the required de facto duration to complete the program may vary highly significant by university. One of the main reasons of this is the fact that the required level of courses or research complexity and quality of a thesis also can vary greatly, e.g. in "very high research activity" elite universities students who are admitted to a "very high research" master (thesis), have to fulfill course and thesis level requirements at a regular PhD level, however.

By contrast, in some cases, such as the integrated master's degree in the UK, the degree is combined with a Bachelor of Science, as a 4-year degree. Unlike a traditional MSc, the fourth year finishes at the same time as undergraduate degrees in the early summer, whereas traditional MSc students typically spend the summer vacation completing a dissertation and finish in September. Examples include MMath (see also Part III of the Mathematical Tripos at Cambridge), MEng and MSci (not to be confused with an MSc).

In the recently standardized European System of higher education (Bologna process), a master degree programme normally carries 90 - 120 ECTS credits, with a minimum requirement of at least 60 ECTS credits at master level (one- or two-year full-time postgraduate program) undertaken after at least three years of undergraduate studies. It provides higher qualification for employment or prepares for doctoral studies. As one ECTS credit is equivalent to 25 hours of study this means that a master's degree programme should include 2250 hours of study. Current U.K. MSc/MA programmes tend to include 1800 hours of study (or 180 UK credits), although many claim to be equivalent to an ECTS accredited master degree.

Admission[edit]

In countries in which a master's degree is a postgraduate degree, admission to a master's program normally requires holding a bachelor's degree, and in the United Kingdom, Canada and much of the Commonwealth, an "honours" bachelor degree.^{[citation needed]} In both cases, relevant work experience may qualify a candidate. In some cases the student's bachelor's degree must be in the same subject as the intended master's degree (e.g. a Master of Economics will typically require a bachelor's degree with a major in economics), or in a closely allied, "cognate", discipline (e.g. Applied Mathematics degrees may accept graduates in physics, mathematics or computer science); in others, the subject of the bachelor's degree is unimportant (e.g. MBA) although, often in these cases, undergraduate coursework in specific subjects may be required (e.g. some M.S.F.degrees require credits in calculus for admission, but none in finance or economics); see also under Business education#Postgraduate education. Most competitive programs also have a grade point average (GPA) that the student must have achieved in their undergraduate degree.

Comparable European degrees[edit]

In some European countries, a magister is a first degree and may be considered equivalent to a modern (standardized) master's degree (e.g., the German and Austrianuniversity Diplom/Magister, or the similar 5-year Diploma awarded in several subjects in Greek, Spanish, Polish, Portuguese, and other universities and polytechnics).

In Denmark the title candidatus or candidata (female) abbreviated cand. is used as a master's equivalent. Upon completion of for instance, an engineral master's degree, a person becomes cand.polyt. (polytechnical). Similar abbreviations, inspired by Latin, apply for a large number of educations, such as sociology (cand.scient.soc), economics (cand.merc., cand.polit. or cand.oecon), law (cand.jur), humanities (cand.mag) etc. A cand. title requires the obtainment of a master's degree. In Finland and Sweden, the title of kand. equates to a bachelor's degree.
In France, the equivalent of master's degrees is the combination of two individual diplomas the master 1 (M1) and master 2 (M2), following the Bologna Process. Depending on the goal of the student (a doctorate or a professional career) the master 2 can also be called a "Master Recherche" (research master) and a "Master Professionnel" (professional master), each with different requirements. To obtain a national diploma for the master 2 requires a minimum of one year of study after the master 1; however, a master 2 often requires 2 years, depending on the university's unique requirements. This is often the case with the Master Recherche as it requires time to conduct research and write a thesis. A French "diplôme d'Ingénieur" is also the equivalent of a master's degree, provided the diploma is recognised by the Commission des titres d'ingénieur.
In Italy the master's degree is equivalent to the two-year Laurea magistrale, which can be earned after a Laurea (a three-year undergraduate degree, equivalent to a bachelor's degree). In particular fields, namely law, pharmacy and medicine, this distinction is not made. University courses are therefore single and last five to six years, after which the master's degree is awarded (in this case referred to as Laurea magistrale a ciclo unico). The old Laurea degree (Vecchio Ordinamento, Old Regulations), which was the only awarded in Italy before the Bologna process, is equivalent^[2] to the current Laurea Magistrale.
In the Netherlands the titles ingenieur (ir.), meester (mr.) and doctorandus (drs.) may be rendered, if obtained in the Netherlands from a university, after the application of the Bologna process, as: MSc instead of ir., LL.M. instead of mr. and MA or MSc instead of drs.^[3] This is because a single program that led to these degree was in effect before 2002, which comprised the same course load as the bachelor and master programs put together. Those who had already started the program could, upon completing it, bear the appropriate title (MSc, LL.M. or MA), but alternatively still use the old-style title (ir., mr. or drs.), corresponding to their field of study. Since these graduates do not have a separate bachelor’s degree (which is in fact – in retrospect – incorporated into the program), the master’s degree is their first academic degree. Bearers of foreign master's degree are able to use the titles ir., mr. and drs. only after obtaining a permission to bear such titles from the Dienst Uitvoering Onderwijs. Those who received their mr., ir. or drs. title after the application of the Bologna process have the option of signing as A. Jansen, MA or A. Jansen, MSc, depending on the field in which the degree was obtained, since the ir., mr. and drs. titles are similar to a master's degree, and the shortcut MA or MSc may officially be used in order to render such title as an international title.^[4]^[5]^[6]^[7]
In Switzerland, the old Licence or Diplom (4 to 5 years in duration) or a postgraduate DEA is considered equivalent to the master's degree.^[8]
In Slovenia and Croatia, during the pre-Bologna process education, all Academic degrees were awarded after a minimum of four years of university studies and a successful defence of a written thesis are considered equivalent to the master's degree.
In Baltic countries there is a two-year education program that offers a chance to gain a master's degree in interdisciplinary issues. The system offers an education in different areas, such as humanities, environmental and social issues, whilst paying specific consideration to the Baltic Sea area. It is a joint-degree program, which is part of a team effort with four universities. There is the University of Tartu in Estonia, the University of Turku in Finland, Vytautas Magnus University in Lithuania and the University of Latvia. The educational programs are very good; allowing students to be mobile within the system, for example one semester may be taken in a confederate school without paying additional membership or tuition fees. Subsequently after passing the qualifications provided, people may procure teaching qualifications and continue their scholastic research around doctoral studies, or carry on studying within their career in the private or public sector. Graduates of the program, within the Baltic Sea area are also given the chance to continue onwards with their studies within the postgraduate system if they have studied the social sciences or humanities field.
In Greece, the metaptychiako which means post-graduate (degree) and is normally two-year after a four-year undergraduate ptychio which means degree.

South America[edit]

Brazil[edit]

In Brazil, after a regular graduation, students have the option to continue their academic career through a master (a.k.a. strictu sensu) or post-graduation (a.k.a. latu sensu) degrees.

At the master's degree ("mestrado", in Portuguese, also referred as "strictu sensu") there are 2–3 years of full-time graduate-level studies. Usually focused on academic research, the master's degree (on any specific knowledge area) requires the development of a thesis, presented (and defended) to a board of PhDs after the period of research. Differently, the "Post-graduation" degree (also referred as "latu-sensu"), also comprehends a 1–2 years studies, but do not require a new thesis to be purposed and defended, being usually attended by professionals looking for a complimentary formation on a different knowledge area than their original graduation.

In addition, a great part of Brazilian universities offers a MBA (Master of Business Administration) degree. Those, nevertheless, are not the equivalent of US MBA degree though, as it does not formally certifies the student/professional with a master's degree (strictu-sensu) but a post-graduation degree instead. A regular post-graduation course has to comply with a minimum of 360 class-hours, while a MBA degree has to comply with a minimum of 400 class-hours. Master's degree (strictu sensu) does not requires minimum class-hours, but it's practically impossible to finish it before 1,5 year due the workload and research required; an average time for the degree is 2,5 years.

Post-graduation (latu sensu) and MBA degrees can be also offered as distance education courses, while the master's degree (strictu-sensu) requires physical attendance.

Often serves as additional qualification for those seeking a differential on the job market, or for those who want to pursue a PhD. It corresponds to the European (Bologna Process) 2nd Cycle or the North American master's.

Asia[edit]

Hong Kong[edit]

MArch, MLA, MUD, MA, MSc, MSocSc, MSW, MEng, LLM[edit]

Hong Kong requires one or two years of full-time coursework to achieve a master's degree.

For part-time study, two or three years of study are normally required to achieve a postgraduate degree.

MPhil[edit]

As in the United Kingdom, MPhil or Master of Philosophy is a research degree awarded for the completion of a thesis, and is a shorter version of the PhD.

Pakistan[edit]

In Pakistani education system, there are two different master degree programmes:

2 years master programmes: These are mostly Master of Arts (MA) leading to Mphil.
4 years master programmes: These are mostly Master of Science (MS) leading to PHD.

Both MA and MS or MSc are offered in all major subjects.

India[edit]

In the Indian system, a master's degree is a postgraduate degree following a Bachelor's degree and preceding a Doctorate, usually requiring two years to complete. The available degrees include:

MA - Master of Arts
MCA - Master of Computer Applications
MCM - Master of Computer Management
ME - Master of Engineering
M.Phil. - Master of Philosophy
MSc - Master of Science
MSc IT - Master of Science in Information Technology
M.Tech - Master of Technology
M.Stat - Master of Statistics
LL.M. - Master of Laws
M.Com - Master of Commerce

Israel[edit]

MA, MSc, MBA: Post-graduate studies in Israel require the completion of a bachelor's degree and is dependent upon this title's grades. There exists also a direct track to a doctorate degree for graduate students, which lasts four to five years. Taking this route, the students must prepare a preliminary research paper during their first year, they then have to pass an exam after which they are automatically awarded a master's degree.
MEng: This is relatively new degree, given by private colleges.

Taiwan[edit]

In Taiwan, bachelor degrees are about four years (with honors) and there is an entrance examination required for people who want to study in master and PhD degrees. The course offered for master and PhD normally is research-based.

The most Foreign Friendly Programs in Taipei, Taiwan are at

1) National Taiwan University College of Management- Global MBA (MBAs in Finance, Accounting, Managemenet, International Business and Information Management)

2) National ChengChi University - IMBA

Programs are entirely in English and Tuition fee cost less than would be paid in North America. As little as US$5000 for an MBA.^{[citation needed]}

As an incentive to increase the number of foreign students, the government of Taiwan and universities have made extra efforts to provide a range of quality scholarships available^{[citation needed]} These are university specific scholarships ranging from Tuition waivers, up to NT$20,000 per month. The government offers the Taiwan Scholarship ranging from 20,000-30,00 per month for 2 years. (US$18,000 - US$24,000 for a 2 year program)

2014-11-14T01:11:00.001-08:00

Children's Day

From Wikipedia, the free encyclopedia

Children's Day
Wikipedia Logo for Children's Day
Observed by	Worldwide
Date	1 June ; 20 November
Frequency	annual
Related to	International Men's Day,International Women's Day,Father's Day, Mother's Day,Parents' Day

Children's Day in Donetsk, Ukraine, 2013

Children's Day is recognized on various days in many places around the world, to honor children globally. It was first proclaimed by the World Conference for the Well-being of Children in 1925 and then established universally in 1954 to protect an "appropriate" day.^[1]

International Day for Protection of Children, observed in many countries as Children's Day on June 1 since 1950, was established by the Women's International Democratic Federation on its congress in Moscow (22 November 1949). Major global variants include aUniversal Children's Day on November 20, by United Nations recommendation.^[2]

[hide]

Universal Children's Day[edit]

Universal Children's Day takes place annually on November 20.^[3] First proclaimed by the United Nations General Assembly in 1954, it was established to encourage all countries to institute a day, firstly to promote mutual exchange and understanding among children and secondly to initiate action to benefit and promote the welfare of the world's children.

This day is observed to promote the objectives outlined in the Charter and for the welfare of children. On November 20, 1958 the United Nations adopted the Declaration of the Rights of the Child.^[4] The United Nations adopted the Convention on the Rights of the Child on November 20, 1989 and can be found here .

In 2000, the Millennium Development Goals outlined by world leaders in order to stop the spread of HIV/AIDS by 2015. Albeit this applies to all people, the main objective is with regard to children.^[4] UNICEF is dedicated to meeting the six of eight goals that apply to the needs of children so that they are all entitled to basic rights written in the 1989 international human rights treaty.^[5] UNICEF delivers vaccines, works with policymakers for good health care and education and works exclusively to help children and protect their rights.^[5]

In September 2012, the Secretary-General Ban Ki-moon of the United Nations led the initiative for the education of children.^[6] He firstly wants every child to be able to attend school, a goal by 2015.^[6] Secondly, to improve the skillset acquired in these schools.^[6] Thirdly, implementing policies regarding education to promote peace, respect and environmental concern.^[6]

Universal Children's Day is not simply a day to celebrate children for who they are, but to bring awareness to children around the globe that have succumbed to violence in forms of abuse, exploitation and discrimination. Children are used as labourers in some countries, immersed in armed conflict, living on the streets, suffering by differences be it religion, minority issues, or disabilities.^[7] Children feeling the effects of war can be displaced because of the armed conflict and/or suffer physical and psychological trauma.^[8] The following violations are described in the term "children and armed conflict": recruitment and child soldiers, killing/maiming of children, abduction of children, attacks on schools/hospitals and not allowing humanitarian access to children.^[8] Currently there are about 153 million children between the ages of 5 and 14 who are forced into child labour.^[9] The International Labour Organization in 1999 adopted the Prohibition and Elimination of the Worst Forms of Child Labour including slavery, child prostitution and child pornography.^[9]

A summary of the rights under the Convention on the Rights of the Child can be found here^[10].

Canada co-chaired the World Summit for children in 1990 and in 2002 the United Nations reaffirmed the commitment to complete the agenda of the 1990 World Summit. This added to the UN Secretary-General's report We the Children: End-of Decade review of the follow-up to the World Summit for Children.

The United Nations children's agency released a study referencing the population increase of children will make up 90 per cent of the next billion people.^[11]

Dates around the world[edit]

The officially recognized date of Children's Day varies from country to country. This section lists some significant examples, in order of date of observance.

Gregorian calendar
Occurrence	Dates	Country
First Friday of January	Jan 4, 2013 Jan 3, 2014 Jan 2, 2015	Bahamas
January 11		Tunisia
Second Saturday of January	Jan 12, 2013 Jan 11, 2014 Jan 10, 2015	Thailand
Second Sunday of February	Feb 10, 2013 Feb 9, 2014 Feb 8, 2015	Cook Islands Nauru Niue Tokelau Cayman Islands
First Sunday of March	March 3, 2013 March 2, 2014 March 1, 2015	New Zealand
March 17		Bangladesh
April 4		Hong Kong Republic of China
April 5		Palestine
April 12		Bolivia Haiti
Last Saturday of April^[12]	Apr 27, 2013 Apr 26, 2014 Apr 25, 2015	Colombia
April 23		Turkey
April 24		Zambia
April 30		Mexico
May 5		Japan South Korea
Second Sunday of May	May 12, 2013 May 11, 2014 May 10, 2015	Spain
May 10		Maldives
May 17		Norway
Nigeria
Last Sunday of May	May 26, 2013 May 25, 2014 May 31, 2015	Hungary
Ascension Day	May 9, 2013 May 29, 2014 May 14, 2015	American Samoa Falkland Islands Solomon Islands
June 1		Albania Angola Armenia Azerbaijan Belarus Benin Bulgaria Bosnia and Herzegovina	People's Republic of China Cambodia Czech Republic East Timor Ecuador Estonia Ethiopia Ecuador Georgia	Guinea-Bissau Kazakhstan Kosovo Kyrgyzstan Laos Latvia Lebanon Lithuania Macedonia Macau	Moldova Mongolia Montenegro Mozambique Myanmar Nicaragua Poland	Portugal Romania Russia São Tomé and Príncipe Serbia Slovakia Slovenia	Tajikistan Tanzania Turkmenistan Ukraine Uzbekistan Vietnam Yemen
June 2		North Korea
Second Sunday of June	Jun 9, 2013 Jun 8, 2014 Jun 14, 2015	United States of America
July 1		Pakistan
Third Sunday of July	Jul 21, 2013 Jul 20, 2014 Jul 19, 2015	Cuba Panama Venezuela
July 23		Indonesia
July 24		Vanuatu
First Sunday of August	Aug 4, 2013 Aug 3, 2014 Aug 2, 2015	Uruguay
Second Sunday of August	Aug 11, 2013 Aug 10, 2014 Aug 9, 2015	Argentina
August 16		Paraguay
Third Sunday of August	Aug 18, 2013 Aug 17, 2014 Aug 16, 2015	Peru
September 9		Costa Rica
September 10		Honduras
Bhadra 29	Sept 14 Sept 15(leap year)		Nepal
September 20		Germany
October 1		El Salvador Guatemala Sri Lanka
First Friday of October	Oct 4, 2013 Oct 3, 2014 Oct 2, 2015	Singapore
First Wednesday of October (Children’s Day recognition and assignation) Second Sunday of August (Children’s Day observance)	Oct 2, 2013 Oct 1, 2014 Oct 7, 2015	Chile
October 8		Iran
October 12		Brazil
Fourth Saturday of October	Oct 26, 2013 Oct 25, 2014 Oct 24, 2015	Australia Malaysia
First Saturday of November	Nov 2, 2013 Nov 1, 2014 Nov 7, 2015	South Africa
November 11		Croatia
November 14		India
November 20		Arab World Azerbaijan Canada Croatia Egypt Ethiopia Finland France Greece Ireland Israel				Kenya Malaysia Macedonia Netherlands Philippines Russia Serbia Slovenia South Africa Spain Sweden Switzerland United Arab Emirates Trinidad and Tobago
December 5		Suriname
December 23		South Sudan Sudan
December 25		Congo Congo DR Cameroon				Equatorial Guinea Gabon Chad Central African Republic
Last Friday of December	Dec 27, 2013 Dec 26, 2014 Dec 25, 2015	Dominica

Argentina[edit]

In Argentina, Children's Day (Día del Niño) is celebrated on the second Sunday of August.

Armenia[edit]

In Armenia, Children's Day is celebrated on June 1.

Australia[edit]

Children's Week is an annual event celebrated in Australia during the fourth week in October, from the Saturday before Universal Children's Day to the following Sunday. Until 1977 Child Care Week was held in various Australian states and territories focusing on children in care or those in institutions. It was held at different times. In 1985 it was decided to coordinate a national week to include all children.^[13]

Bangladesh[edit]

In Bangladesh, Children's Day is celebrated on March 17. It is also the birthday of Bangabandhu Sheikh Mujibur Rahman.

Bolivia[edit]

In Bolivia, Children's Day (Día del Niño) is celebrated on April 12.

Brazil[edit]

In Brazil, Children's Day (In Portuguese: Dia das Crianças) is celebrated on October 12, coinciding with Our Lady of Aparecida's day, the country's Patron Saint, which is holiday. In Brazil Children's day is celebrated by kids receiving presents from their parents.

Bulgaria[edit]

In Bulgaria, children's day is celebrated on June 1.^[14] Traditionally kids receive very special attention from their family, including Birthday-like presents. In the past all drivers were expected to drive with their lights on all day long to demonstrate extra vigilance over children's safety. Now it is compulsory to drive with the lights on every day of the year.

Canada[edit]

National Child Day has been proclaimed across Canada since 1993 to commemorate the United Nations' adoption of two documents centered on children's rights: the United Nations Declaration of the Rights of the Child on November 20, 1959, and the United Nations Convention on the Rights of the Child on November 20, 1989.^[15] The "Child Day Act" outlines human rights to which children, under the age of 18, are entitled by law. This Act promotes awareness and teaches children that they have rights, like adults do, under the law.^[15] The date of celebration is November 20.^[15]

Central Africa[edit]

In Congo, Congo DR, Cameroon, Equatorial Guinea, Gabon, Chad, Central African Republic, Children's Day is celebrated on December 25 to honor all the children there.

Chile[edit]

In Chile, Children's Day is officially recognized, and assigned to the first Wednesday of October. However, it is observed on the second Sunday of August.^[16] It retains none of the international flavor as a day to recognize the needs of or rights of children, but is observed merely as a commercial holiday dedicated to buying toys for children.

People's Republic of China[edit]

Children's Day (PRC)

Traditional Chinese

六一國際兒童節

Simplified Chinese

六一国际儿童节

[show]Transcriptions

In the People's Republic of China, Children's Day is celebrated on June 1 and is formally known as "the June 1 International Children's Day" (Chinese: 六一国际儿童节; pinyin: Liù Yī Guójì Értóng Jié). When the People's Republic of China was first established in 1949, the State Council (Cabinet) designated a half-day holiday for all primary schools on June 1. This was later made into a full day's break in 1956 with The Announcement by the State Council to make June 1 Children's Day a One-Day Holiday. Schools usually hold activities such as children's performances, camping trips, or free movies on Children's Day or the day before to allow students to have fun. Children of civil servants might also receive small gifts from the government until they are fourteen, and Civil servants who have children sometimes have a half-day holiday on June 1 to spend more time with their children. Entrance and set out ceremonies of the Young Pioneers of China are usually held on June 1 as well. Entrance of children under 14 into the Forbidden City is free on June 1, while each accompanying adult gets 50% off, i.e. CNY30.

Colombia[edit]

In Colombia, Children's Day is celebrated in the last Saturday of April .

Costa Rica[edit]

In Costa Rica, Children's Day is celebrated on September 9.

Croatia[edit]

In Croatia, Children's Day is celebrated on November 11.

Cuba[edit]

In Cuba, Children's Day is celebrated on the third Sunday of July.

Czech Republic[edit]

In Czech Republic, Children's Day is celebrated on June 1.

Children's day (Día del Niño) in Ecuador

Ecuador[edit]

In Ecuador, Children's Day (Día del Niño) is celebrated on June 1. Generally, kids up to 12 years old receive presents.

Egypt[edit]

In Egypt, Children's Day is celebrated every November 20 with festivals and games for children.

Finland[edit]

In Finland, Children's Day is known as Day of Children's Rights and is celebrated on 20 November.

Former and current Communist and Socialist countries[edit]

1997 stamp of Belarus

In Russia, as well as other former Soviet Union states, including Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan,Latvia, Lithuania, Moldova, Tajikistan, Turkmenistan, Ukraine, Uzbekistan, other former or current communist states, Albania, Angola,Benin, Bosnia and Herzegovina, Bulgaria, Cambodia, Croatia, Cuba, Czech Republic, Slovakia, Ethiopia, East Germany, Kosovo, Laos,Republic of Macedonia, Mongolia, Montenegro, Mozambique, Poland, Romania, Serbia, Slovenia, Tanzania and Yemen, Children's Day is celebrated on June 1.

This list includes 25 countries which regained independence from USSR, seceded from Yugoslavia Federation, as well as Czechoslovakiaand Ethiopia after their respective splits.

Germany[edit]

Burning of "trash and filth" literature by students and "Young Pioneers" at the 18th Elementary school in Berlin-Pankow (Buchholz), East Berlin, on the evening of International Children's Day, June 1, 1955

In Germany, during the Cold War, Children's Day (Kindertag) was handled quite differently in West Germany and East Germany. While East Germany (GDR) celebrated International Children's Day (Internationaler Kindertag) on June 1,West Germany (FRG) celebrated Universal Children's Day (Weltkindertag) on September 20.

The customs of Children's Day were also significantly different in West and East Germany. In East Germany, the holiday was introduced in 1950, and was from then held on a yearly basis for the children. On this day of the year, children would typically be congratulated and would receive presents from their parents and did special activities in school, such as field trips and the like.

In West Germany, Children's Day Universal Children's Day laid its emphasis not on games and presents, but more on political efforts to strengthen children's rights.^{[citation needed]} (See Jugendamt.)

After the reunification of East and West Germany occurred in 1990, Universal Children's Day has become official for whole Germany. This, however, was not accepted by large parts of the East German population. Most parents still celebrate Children's Day on the former date of June 1, and public events pertaining to Children's Day take place on September 20 (Weltkindertag).^[17]^[18]

Guatemala[edit]

In Guatemala, Children's Day is celebrated on October 1.

Honduras[edit]

In Honduras, Children's Day is celebrated on September 10.

Hungary[edit]

Children's Week began in Hungary in 1931. Since 1950 it has been reduced to Children's Day, taking place on the last Sunday in May.^[19]

Haiti[edit]

In Haiti, Children's Day is celebrated on April 12. It took the place with Universal Children's Day on December 1.

Hong Kong[edit]

Children's Day (Chinese: 兒童節; Jyutping: ji4 tung4 zit3) is celebrated on April 4, having been established in 1931 at the same time as the Republic of China (Taiwan).

Indonesia[edit]

In Indonesia, Children's Day is celebrated on July 23. but in Batam, specifically SEKOLAH MONDIAL celebrates WCD on the 23–24 October. A lot of programmes are held such as : Field Demo Dance, Band Performances, Games, Booths and a lot more. Everything is performed by the students of Mondial from Kindergarten to High School Level .

India[edit]

Nehru distributes sweets among children at Nongpoh, Meghalaya

In India, Children's Day is celebrated on 14 November, the birthday of the country's first Prime Minister Jawaharlal Nehru. Jawaharlal Nehru, who was fondly called Chacha Nehru (Uncle Nehru) or Chaffinch (Uncle) by the kids, emphasized the importance of giving loveand affection to children, whom he saw as the bright future of India. He wanted to enhance the progress of Indian youth for which he established education institutes like AIIMS, Indian Institute of Technology. It is well known that Jawaharlal Nehru admired 3 things, first one of which is the flower rose, second one being in the company of women, and the third was with the children. To give him tribute, Indiacelebrates this festival on 14 November, the day of his birthday.^[20]

Many functions are organized in schools, offices and other organizations. Most schools hold cultural performances on this day, run by the children themselves. Teachers also get involved, and may perform songs and dances for their students. On this day, the State and the Central Government also make it a point to showcase children's films as part of Film festivals organized in many parts of the country. All over the country, various cultural and social institutions conduct competitions for children. Children's Day is seen as a day for the kids to engage in fun. Children take part in many sports organized for them.

Ireland[edit]

In Ireland, Children's day is celebrated on November 20.

Palestine[edit]

In Palestine, Children's Day is celebrated on November 20

Japan[edit]

Japan's Children's Day (子供の日 kodomo no hi^?) is celebrated on May 5, a National Holiday since 1948, to celebrate the happiness of all children and to express gratitude toward mothers. There is a long tradition, from the 8th century, to celebrate children's day twice a year; March 3 for girls and on May 5 for boys. On March 3, also known as theDoll Festival, Japanese people decorate their households with traditional Heian Period doll sets and plum blossom, and drink Amazake. On May 5, also known as 端午の節句 (tango-no sekku), they fly carp streamers outside, display Samurai dolls, and eat chimaki.

There were some who argued in 1948 that March 3 should also be a National Holiday.

Kazakhstan[edit]

The International Children's Day is celebrated annually on June 1 and is established as a national holiday for children. Over 3 million children across Kazakhstan celebrate the holiday with special children events, including charity events for raising awareness of global problems such as child abuse and child labour abuse.

North Korea[edit]

North Korean Children's Day is celebrated on June 2 as the International Children's Day (국제 아동절). Before 1945, it was celebrated on May 1. There is also a day called 조선소년단창립절(Festival for establishment of Young Pioneer Corps) on June 6.

Republic of Korea[edit]

Children's day in Seoul, South Korea, May 5, 1954

In South Korea, May 5 is officially recognized as Children's Day (어린이날). Parents often give presents to their children, as well as spend time with them. The children are taken on excursions to zoos, museums, and various venues of children-oriented entertainment.

Children's Day was first conceived by innovative Korean students and social leaders on the basis of the March 1st Movement to achieve Korean independence from Japanese colonialism. From Jinju, many people gathered to promote and improve the social status of children and encourage adults to teach awareness of their deprived sovereignty. In 1923,^[21] several groups of students studying in Tokyo agreed to designate May 1 as Children's Day. A predominant intellectual figure, Bang jeong hwan (방정환,方定煥), greatly contributed to the popularization of the holiday. Because it overlapped with Laborer's Day, Children's Day was moved to May 5. Bang Jeon Hwan first coined the modern Korean word for children, eorini (어린이), replacing the previous words aenom (애놈) and aesaekki (애새끼).^[22] Until 1939, Japanese authorities based in Seoul oppressed the movement to stop Korean social activists congregating for the festival. After independence in 1945, the movement to respect children was revived. The children's welfare law written in the constitution officially designated May 5 as Children's Day in 1961. And by 'the law of holiday of government office', Children's day became a holiday in Korea in 1970.^[23]

Laos[edit]

In Laos, Children's Day is celebrated on June 1.

Malaysia[edit]

In Malaysia, Children's Day is celebrated on the first Saturday of November annually. Primary school pupils normally go to school on the Friday before the event to celebrate Children's Day. The schools that are involved would also organize numerous activities for their pupils.

Maldives[edit]

Children's Day celebration in Kendhoo, Maldives

In Maldives, Children's Day is celebrated on May 10. It is a public holiday and primary schoolchildren go to school to the event to celebrate Children's Day. The schools that are involved would also organize numerous activities for their pupils.

Myanmar[edit]

In Myanmar, Children's Day is celebrated on 1 June.

Mexico[edit]

In Mexico, Children's Day is celebrated on April 30. It is also known as "El Día Del Niño". On this day teachers in schools organize the day for their children. In some schools, lessons are suspended for the day. They organize games, music, and the children bring in their favorite foods to share with others. Some families also have a day out with their children. There are special activities for the children in parks and sports centers. Sometimes, also, the children will be given presents by their families. This is the day when children are honored in Mexico. Children's Day in Mexico started in 1925.

Mongolia[edit]

In Mongolia, the International Children's Day is celebrated on June 1. It is also known as "Эх үрсийн баяр".

Mozambique[edit]

In Mozambique, the International Children's Day is also celebrated on the 1st of June .

Nepal[edit]

In Nepal, Children's Day (बाल दिवस) is celebrated on Bhadra 29 according to the Nepali Calendar(Sept 14 or September 15(Leap Year)). Earlier during the Shah Rule, Nepal used to observe Children's day on Bhadra 4 on the birthday of H.M. Queen Mother Ratna Rajya Laxmi Devi Shah.

New Zealand[edit]

In New Zealand, Children's Day is typically celebrated on the first Sunday in March. It honours children as a taonga (Maori for treasure) and is a day families can relax and share in activities that honour this. This year, 2012, the focus is on peace and aroha (Maori for love). New Zealand has high rates of child abuse and family violence. The Government has recognised this as one of the most important issues for New Zealanders, with an event such as Children's Day helping to focus on the practice of sharing, loving and caring as well as honouring "tamariki" (Maori for children).

Nigeria[edit]

Children's Day is celebrated on May 27 in Nigeria. It is a public holiday for Primary and Secondary school children. Due to the large size of the country, only few group of children (schools or any other organization) are selected to march past parade. The children are usually given treats such as an outing or doing jobs that adults would normally do. In some situations, primary and secondary school children compete in military parades format for a prize which will be given at the end of the competition. Religious groups in Nigeria also celebrate children's day in grand style. Many private and public organizations usually put together children's party for privileged and less privileged children in a bid to give them a sense of belonging. It is also a day media organizations analyze the plight of children in the society and efforts government and non government agencies make to better the lot of children.

Nicaragua[edit]

In Nicaragua the International Children's Day is celebrated on June 1.

Norway[edit]

Children's Day in Norway is held on May 17, the same day as Norwegian Constitution Day, with many children's parades simultaneously celebrating both events and thereby emphasizing the importance of children in Norwegian society.

Pakistan[edit]

In Islamic Republic of Pakistan,Children's Day is celebrated on the 1st of July.In Punjab the Child Rights Cell of Department of Social Welfare Punjab collaborates with UNICEF to celebrate this day. Whereas, The NGO, Voice of Children Islamabad, also celebrates Children'a day and arranges activities for children and parents on that day. The EPO and SFB also celebrate Children's day and arrange fun and interactive sessions for children and parents.

For Children's Day, there are many festivals and events organised by schools and organisations, that focus on having fun and lively activities that kids and their families can enjoy. Most charitable organisations also partake in the festivities, by holding functions or partnering with bigger organisations. Thus, everyone joins in to make this day a memorable event each year in Pakistan.

Palestine[edit]

Children day is celebrated in Palestine on April 5, there are festivals, celebrations and activities children can enjoy.^{[citation needed]}

Panama[edit]

In Panama, Children's Day or Kid's Day was formerly held on November 1, but was changed by Vivian Fernandez de Torrijos, the wife of President Martin Torrijos (2004–2009), to the third Sunday of July.^[24]

Paraguay[edit]

In Paraguay, Children's Day is celebrated on August 16, day of the Battle of Acosta Ñu, where it is said that 20,000 men from the Triple Alliance were awaited by a Paraguayan force made up of 3,500 children ages six to fifteen, ordered to hold the Alliance forces while the president Solano Lopez could escape. Even though Paraguay had been already completely defeated, it is said that Lopez forced them to stay and face the enemy, others sources claim that the children volunteered to fight against the Allied forces after their families had been killed by the advancing allied forces (see more in Paraguayan War). Children's Day is a national holiday, used to remember the event, which happened during the five-year war.

Peru[edit]

According to Peruvian law in Peru, Children's Day (Día del Niño Peruano (Ley Nº 27666) , literally Peruvian Children's Day (Law Nº 27666)) is celebrated every third Sunday of August. On this day of the year, Peruvian children would typically be congratulated and would receive presents from their parents. Since it is celebrated on Sunday, all special activities in school, such as field trips and the like are done the previous Friday. All major stores offer special discounts on toys, appliances, electronics, clothes, etc.

Philippines[edit]

The Senate of the Philippines approved on third and final reading a bill declaring every December 25 as National Children's Day to promote consciousness over the protection of the rights of Filipino children.^[25]

Poland[edit]

In Poland, Children's Day (Dzień Dziecka) is celebrated on June 1. The International Children's Day was introduced in Poland in 1952. It coincides with the beginning of summer and it is usually treated as a holiday, as it takes place near the end of the school year. Schools usually organize special activities for the day of the celebration, and the first week of June is a time of festivities organized in parks and entertainment centers for children. Parents buy small gifts for their children.

Portugal and former colonies[edit]

In Portugal (and also at some of its former colonies such as Guinea-Bissau, Macau, Cape Verde, East Timor, Angola, Mozambique and São Tomé and Príncipe), Children's Day (Dia da Criança) is celebrated on June 1.

Romania[edit]

In Romania, Children's Day (Romanian: “Ziua Copilului”) is celebrated on June 1. Various events are also organized.

On June 1, 2012, International Children's Day was celebrated by the Romanian Government at the Ministry of Labour, Family and Social Protection.^[26] Almost 100 children in attendance received a Minister of Children diploma celebrating with parents and grandparents.^[26]

Russian Federation[edit]

Children of Vladivostok, Russian Federation celebrating the International Children's Day

Participants compete at the baby crawling contest held in Volgogradahead of the International Children's Day, 2011

In Russia, Children's Day is celebrated on June 1.

Singapore[edit]

Traditionally, October 1 is the day which Singapore officially celebrates Children's Day, a similar event celebrated every year is Youth Daywhich is celebrated on the first Sunday of July every year. Kindergarten and primary school children in Singapore do not have to attend school on this day. From 2011, Children's Day was celebrated on the first Friday of October.

South Africa[edit]

In South Africa, Children's Day is on the first Saturday of November but not really celebrated in any significant way.^[27]

South Sudan[edit]

In South Sudan, Children's Day is celebrated on December 23, the birthday of South Sudan's "greatest child" according to tribal mythology.

Slovakia[edit]

In Slovakia, the day is called International Children's Day (Medzinárodný deň detí) and is celebrated on June 1. Children get a free entrance to some attractions like zoos.^{[citation needed]}.

Spain[edit]

In Spain, this date is celebrated on the 2nd Sunday of May, and it is called "Día del niño"

Sri Lanka[edit]

In Sri Lanka, Children's Day is celebrated on October 1.

Sudan[edit]

In Sudan, Children's Day is celebrated on December 23, the birthday of North Sudan's "greatest child" according to tribal mythology.

Suriname[edit]

In Suriname, Children's Day or Kinderdag is celebrated on December 5. Generally, children up to 12 years old receive presents from their parents.

Sweden[edit]

In Sweden, Children's Day is celebrated on the first Monday of October. It was Gustav Rosén who is credited with starting a Children's Day in Umeå in northern Sweden in 1905.^[28]

Taiwan[edit]

Children's Day (ROC)

Traditional Chinese

婦女節、兒童節合併假期

Simplified Chinese

妇女节、儿童节合并假期

[show]Transcriptions

The Republic of China designated April 4 as Children's Day (Chinese: 兒童節; pinyin: Értóng Jié), pursuant to Article 5 of the Order to Implement Commemoration Days and Holidays.^[29] The holiday dates back to 1931 and since then schools often hold special activities in order to celebrate the occasion. Because of pressure from parents demanding to accompany their children in the celebration, Taiwan celebrated Women's Day together with Children's Day on April 4, 1991. Since then, April 4 has been known as "The Combined Holidays of Women's Day and Children's Day" (Chinese: 婦女節、兒童節合併假期). It has been a public holiday of Taiwan since 2011.^[30]

Thailand[edit]

Children's Day 2012 at the Chiang Mai Royal Thai Air Force base

Thailand National Children's Day (Thai: วันเด็กแห่งชาติ) is celebrated on the second Saturday in January. Known as “Wan Dek” in Thailand, Children’s Day is celebrated to give children the opportunity to have fun and to create awareness about their significant role towards the development of the country.

Usually, His Majesty the King gives advice addressing the children while the Supreme Monarch Patriarch of Thailand gives a moral teaching. The Prime Minister also usually gives each Children's Day a theme and a slogan.

Many Government offices are open to children and their family; this includes the Government House, the Parliament House Complex and various Military installations. These events may include a guided tour and an exhibition. A notable example is the guided tour at the Government House, where children have an opportunity to view the Prime Minister's office and sit at the bureau. The Royal Thai Air Force usually invites children to go and explore the aircraft and the Bangkok Bank distributes stationery, such as pens, pencils and books to every child that enters the bank as a community service. Many organizations from both government and commercial sectors have celebration activities for children. Children can enter zoos or ride buses for free.

There is a Thai saying that states, "Children are the future of the nation, if the children are intelligent, the country will be prosperous."

Trinidad and Tobago[edit]

International Men's Day on 19 November followed by Universal Children's Day on 20 November form a 48 hour celebration of men and children respectively in Trinidad andTobago.^[31]

Tunisia[edit]

Children's Day in Tunisia is celebrated on January 11 every year. It is a day in which Tunisians observe the rights of children and remind themselves that children are the future builders and developers of the country and the world.

Turkey[edit]

"The Holiday of National Sovereignty and Children", celebrated in Germany, in 2011

The Grand National Assembly of Turkey was established on 1920, April 23, and to commemorate the event, April 23 was proclaimed a national holiday in 1921. Since 1927^[32] it has also become Children's Day (Turkish: Ulusal Egemenlik ve Çocuk Bayramı, literally "The Holiday of National Sovereignty and Children"), an official holiday dedicated to the children of Turkey and (from 1979 on) the world. Turkish; April 23 Children's Festival

In addition to holding many domestic celebratory events such as stadium performances, Turkey also houses TRT International April 23 Children's Festival, where groups of children from other countries are invited to participate in the festivities while staying at Turkish families' homes.

Ukraine[edit]

Children's Day in Ukraine

Children's Day (Ukrainian: День захисту дітей, Den zakhystu ditey, literally "day of child's protection") is celebrated in Ukraine on June 1. It was introduced in Ukraine in 2009.^{[citation needed]}

United States of America[edit]

Children's Day observations in the United States predate both Mother's and Father's Day, though a permanent annual single Children's Day observation is not made at the national level.

In 1856, Rev. Charles H. Leonard, D.D., then pastor of the First Universalist Church of Chelsea, Mass., set apart a Sunday for the dedication of children to the Christian life, and for the re-dedication of parents and guardians to bringing-up their children in Christian nurture. This service was first observed the second Sunday in June.^[33]

The Universalist Convention at Baltimore in September 1867, passed a resolution commending churches to set apart one Sunday in each year as Children's Day.^[34]

The Methodist Episcopal Church at the Methodist Conference of 1868 recommended that second Sunday in June be annually observed as Children's Day.^[34]

The General Assembly of the Presbyterian Church in 1883 designated "the second Sabbath in June as Children's Day."^[35]

Also in 1883, the National Council of Congregational Churches and nearly all the state bodies of that denomination in the United States passed resolutions commending the observance of the day. About this time many other denominations adopted similar recommendations.^[34]

Chase's Calendar of Events cites Children's Sunday and notes that The Commonwealth of Massachusetts issues an annual proclamation for the second Sunday in June.^[36]

Numerous churches and denominations currently observe the second Sunday in June including the African Methodist Episcopal Church, African Methodist Episcopal Zion Church, and the Christian Methodist Episcopal Church.

Children & Youth Day in Hawaii started in 1994 when the Hawaii Legislature became the first to pass a law to recognize the first Sunday in October as "Children's Day". In 1997, the Legislature passed another landmark law designating the entire month of October as "Children and Youth Month".

In 1996, author Pat Mora, after learning about the annual Mexican tradition of celebrating April 30 as El día del niño, the Day of the Child, proposed an annual celebration in the U.S. of El día de los niños, El día de los libros/Children's Day, Book Day, thus honoring children and connecting them to literacy, essential in a democracy. Assistance starting this community-based, family literacy initiative was provided by REFORMA, the National Association to Promote Library & Information Services to Latinos and the Spanish Speaking. Often known as Día, because it is both a daily commitment and an annual April celebration, Children's Day, Book Day, has grown to link all children to books, languages and cultures. A major partner is the Association for Library Services to Children (ALSC), a division of the American Library Association (ALA). Every year, across the country, hundreds of libraries, schools, and community organizations, etc. hold culminating April Children's Day, Book Day celebrations that unite communities, creating an annual tradition much like Mother's Day and Father's Day.

Children's Day was proclaimed by President Bill Clinton to be held on October 11, 1998,^[37] in response to a letter written by a six year old boy inquiring if he would make a Children's Day for him. "National Child's Day" was proclaimed by President George W. Bush as June 3, 2001 and in subsequent years on the first Sunday in June.^[38]

Since 2009, Illinois Governor Pat Quinn has issued proclamations proclaiming the second Sunday in June as Children's Day as had the previous governor in 2007 and 2008. The mayors of Aurora and Batavia, Illinois, also have issued proclamations.^[39]

Dates[edit]

2010: June 7

2011: June 6

2012: June 4

2013: June 3

2014: June 8

2015: June 7

2016: June 5

Uruguay[edit]

Children's Day in Uruguay is a decided Sunday in August, is commercially Children's Day. January 6 is Wise Man day, mostly kids receive presents but sometimes adults too. there people celebrate children day with great pomp and show

Vanuatu[edit]

In Vanuatu, Children's Day is celebrated on the July 24. "Stop violence against children", and "Give a child the chance to express their opinion today". After the march there are speeches and activities organized by schools, including a dance. Then, after midday, children return home to spend time with their parents for the rest of the day. Children's Day is a public holiday, set up following a recommendation of the Committee on the Rights of the Child. A group of people in the United Nations monitor and protect children's rights. A committee, with both adult and child members, organizes activities. In the past, a committee of adults has chosen the theme – but in the future children may help choose it.

Children's Day originally took place only in the capital of Vanuatu, but it has now been extended to all 6 provinces. Schools, churches, local governments of the provinces and other local organizations all organize activities. Save the Children supports one Children's Day activity in each province, selecting it from the many requests they receive for support. In 2008, one of the activities supported by Save the Children was a sports day between many different schools.

Parents and caretakers have been supportive of Children's Day activities. Many parents come to activities with children. For example, in one province, children and parents from 5 different schools came together for a shared lunch. Some parents give their children presents for Children's Day – however, Save the Children try to spread the message that it doesn't matter if a parent can't afford to buy their child a present, as the real aim of Children's Day is for parents and children to spend the day together, and work together to reconcile their problems.

Venezuela[edit]

In Venezuela, Children's Day is celebrated the third Sunday of July.

Mid-Autumn Festival in Vietnam

Vietnam[edit]

In Vietnam, Children's Day is celebrated on June 1 as ICD and on the full moon of the 8th lunar month during the Mid-Autumn Festival.

Zambia[edit]

In Zambia, Children's Day celebrates on April 24 before Universal Children's Day on December 25 from Zambia lighting.

The History Of Trousers

2014-11-11T19:26:00.005-08:00

Trousers

This article is about the clothing item. For the implementation of the TCG Software Stack, see Trusted Computing Group.

"Pants" redirects here. For styles of undergarments sometimes called "Underwear", see Underpants and Undergarment. For the object in topology, see Pair of pants (mathematics).

For the British film, see Trousers (1920 film). For the Indian film, see Jeans (film).

A man wearing trousers

Trousers (UK usage, pants elsewhere) are an item of clothing worn from the waist to the ankles, covering both legs separately (rather than with cloth extending across both legs as in robes, skirts, and dresses). In the UK the word "pants" generally means underwear and not trousers.^[1]Shorts are similar to trousers, but with legs that come down only to around the area of the knee, higher or lower depending on the style of the garment. To distinguish them from shorts, trousers may be called "long trousers" in certain contexts such as school uniform, where tailored shorts may be called "short trousers", especially in the UK.

In most of the Western world, trousers have been worn since ancient times and throughout the Medieval period, becoming the most common form of lower-body clothing for males in the modern world, although shorts are also widely worn, and kilts and other garments may be worn in various regions and cultures. Since the mid-20th century, trousers have increasingly been worn by females as well. Jeans, made of denim, are a form of trousers for casual wear, now widely worn all over the world by both sexes. Shorts are often preferred in hot weather or for some sports, and also often by children and teenagers. Trousers are worn at the hips or waist, and may be held up by their own fastenings, a belt, or suspenders(braces). Leggings are form-fitting trousers, of a clingy material, often knitted cotton and spandex (elastane).

Terminology

In the United Kingdom and Ireland the words "trousers", or "slacks", were historically used for women's trousers. ^[2] In Scotland, trousers are occasionally known as trews, which is the historic root of the word 'trousers'. Trousers are also known as breeks in Scots, a word related to breeches. The item of clothing worn under trousers is underpants. The standard form 'trousers' is also used, but it is sometimes pronounced in a manner approximately represented by "tru:zɨrz", which is possibly a throwback to the Gaelic word truis which the English word originates from. In North America pants is the general category term, whereas trousers (sometimes slacks in Australia and the United States) often refer more specifically to tailored garments with a waistband, belt-loops, and a fly-front. So informal elastic-waist knitted garments would be called pants, but not trousers (or slacks).

North Americans call undergarments underwear, underpants, undies, jockey shorts, shorts, long johns or panties (the last are women's garments specifically) to distinguish them from other pants that are worn on the outside. The term drawers normally refers to undergarments, but in some dialects, may be found as a synonym for "breeches", that is, trousers. In these dialects, the term underdrawers is used for undergarments. Many North Americans refer to their undergarments by their type, such as boxers or briefs.

In Australia, men's underwear also has various informal terms including under-dacks, undies, dacks or jocks. In New Zealand men's underwear is known as "undies", or "y-fronts".

Various people in the fashion industry use the words trouser or pant instead of trousers or pants. This is nonstandard usage. The words "trousers" and "pants" are pluralia tantum, nouns that generally only appear in plural form—much like the words "scissors" and "tongs". However, the singular form is used in some compound words, such astrouser-leg, trouser-press and trouser-bottoms.^[3]

History[edit]

Prehistory[edit]

There is some evidence, from figurative art, of trousers being worn in the Upper Paleolithic, as seen on the figurines found at the Siberian sites of Mal'ta and Buret'.^[4] The oldest known trousers are found at the Yanghai cemetery in Turpan, Xinjiang, China, dated to the period between the 13th and the 10th century BC. Made of wool, the trousers had straight legs and wide crotches, and were likely made for horseback riding.^[5]

Antiquity[edit]

Scythian archer. Interior from anAncient Greek Attic red-figure plate, ca. 520–500 BC, from Vulci. British Museum, London.

Germanic trousers of the 4th century found in the Thorsberg moor, Germany

Trousers first enter recorded history in the 6th century BC, with the appearance of horse-riding Iranian peoples in Greek ethnography. At this time, not only the Persians, but also allied Eastern andCentral Asian peoples such as the Bactrians, Armenians, Tigraxauda Scythians and Xiongnu Hunnu, are known to have worn them.^[6]^[7] Trousers are believed to have been worn by both sexes among these early users.^[8] The oldest preserved pair of trousers are thought to be from the 10th to 13th centuries BC and were found in the Yanghai graveyard in China’s Tarim Basin. It is believed the garments were invented to make horse riding easier.^[9]

The ancient Greeks used the term "ἀναξυρίδες" (anaxyrides) for the trousers worn by Easternnations^[10] and "σαράβαρα" (sarabara) for the loose trousers worn by the Scythians.^[11] However, they did not wear trousers since they thought them ridiculous,^[12]^[13] using the word "θύλακοι" (thulakoi), pl. of "θύλακος" (thulakos), "sack", as a slang term for the loose trousers of Persians and other orientals.^[14]

Republican Rome viewed the draped clothing of Greek and Minoan (Cretan) culture as an emblem of civilization and disdained trousers as the mark of barbarians.^[15] As the Empire expanded beyond theMediterranean basin, however, the greater warmth provided by trousers led to their adoption.^[16] Two types of trousers eventually saw widespread use in Rome: the Feminalia, which fit snugly and usually fell to knee or mid-calf length,^[17] and the Braccae, a loose-fitting trouser that was closed at the ankles.^[18] Both garments were adopted originally from the Celts of Europe, although later familiarity with the Persian Near East and the Teutons increased acceptance. Feminalia and Braccae both began use as military garments, spreading to civilian dress later, and were eventually made in a variety of materials including leather, wool, cotton and silk.^[19]

Medieval Europe[edit]

Trousers of various design were worn throughout the Middle Ages in Europe, especially by males. Loose-fitting trousers were worn in Byzantium under long tunics,^[20] and were worn by many tribes, such as the Germanic tribes that migrated to Western Roman Empire in the Late Antiquity and Early Middle Ages, as evidenced by both artistic sources and such relics as the 4th-century costumes recovered from the Thorsberg bog (see illustration).^[21] Trousers in this period, generally called brais, varied in length and were often closed at the cuff or even had attached foot coverings, although open-legged pants were also seen.^[22]

By the 8th century there is evidence of the wearing in Europe of two layers of trousers, especially among upper-class males.^[23] The under layer is today referred to by costume historians as "drawers", although that usage did not emerge until the late 16th century. Over the drawers were worn trousers of wool or linen, which in the 10th century began to be referred to as breeches in many places. Tightness of fit and length of leg varied by period, class, and geography. (Open legged trousers can be seen on the Norman soldiers of the Bayeux Tapestry.)^[24]

Although Charlemagne (742–814) is recorded to have habitually worn trousers, donning the Byzantine tunic only for ceremonial occasions,^[25]^[26] the influence of the Roman past and the example of Byzantium led to the increasing use of long tunics by men, hiding most of the trousers from view and eventually rendering them an undergarment for many. As undergarments, these trousers became briefer or longer as the length of the various medieval outer garments changed, and were met by, and usually attached to, another garment variously called hose or stockings.

In the 14th century it became common among the men of the noble and knightly classes to connect the hose directly to their pourpoints^[27] (the padded under jacket worn with armored breastplates that would later evolve into the doublet) rather than to their drawers. In the 15th century, rising hemlines led to ever briefer drawers^[28] until they were dispensed with altogether by the most fashionable elites who joined their skin-tight hose back into trousers.^[29] These trousers, which we would today call tights but which were still called hose or sometimes joined hose at the time, emerged late in the 15th century and were conspicuous by their open crotch which was covered by an independently fastening front panel, the codpiece. The exposure of the hose to the waist was consistent with 15th century trends, which also brought the pourpoint/doublet and the shirt, previously undergarments, into view,^[30] but the most revealing of these fashions were only ever adopted at court and not by the general population.

Men's clothes in Hungary in the 15th century consisted of a shirt and trousers as underwear, and a dolman worn over them, as well as a short fur-lined or sheepskin coat. Hungarians generally wore simple trousers, only their colour being unusual; the dolman covered the greater part of the trousers.^[31]

Europe before the 1900s[edit]

Around the turn of the 16th century it became conventional to separate hose into two pieces, one from the waist to the crotch which fastened around the top of the legs, called trunk hose, and the other running beneath it to the foot. The trunk hose soon reached down the thigh to fasten below the knee and were now usually called "breeches" to distinguish them from the lower-leg coverings still called hose or, sometimes stockings. By the end of the 16th century, the codpiece had also been incorporated into breeches which featured a fly or fall front opening.

As a modernisation measure, Tsar Peter the Great issued a decree in 1701 commanding every Russian, other than clergy and peasant farmers, to wear trousers.^[32]

During the French Revolution, the male citizens of France adopted a working-class costume including ankle-length trousers, or pantaloons (from a Commedia dell'Arte character named Pantalone)^[33] in place of the aristocratic knee-breeches. The new garment of the revolutionaries differed from that of the ancien regime upper classes in three ways: it was loose where the style for breeches had most recently been form-fitting, it was ankle length where breeches had generally been knee-length for more than two centuries, and they were open at the bottom while breeches were fastened. This style was introduced to England in the early 19th century, possibly^{[original research?]} by Beau Brummell, and by mid-century had supplanted breeches as fashionable street wear.^[34] At this point, even knee-length pants adopted the open bottoms of trousers (see shorts) and were worn by young boys, for sports, and in tropical climates. Breeches proper survived into the 20th century as court dress, and also in baggy mid-calf (or three-quarter length) versions known as plus-fours or knickers worn for active sports and by young schoolboys. Types of breeches are still worn today by baseball and American football players.

Sailors may have played a role in the worldwide dissemination of trousers as a fashion. In the 17th and 18th centuries, sailors wore baggy trousers known as galligaskins. Sailors also pioneered the wearing of jeans, trousers made of denim.^{[citation needed]} These became more popular in the late 19th century in the American West because of their ruggedness and durability.

Starting around the mid-19th century, Wigan pit brow girls scandalized Victorian society by wearing trousers for their work at the local coal mines. They wore skirts over their trousers and rolled them up to their waists to keep them out of the way. Although pit brow lasses worked above ground at the pit-head, their task of sorting and shovelling coal involved hard manual labour, so wearing the usual long skirts of the time would have greatly hindered their movements.

Medieval Korea[edit]

The Korean word for trousers, baji (originally pajibaji) first appears in recorded history around the turn of the 15th century, but pants may have been in use by Korean society for some time. From at least this time pants were worn by both sexes in Korea. Men wore trousers either as outer garments or beneath skirts, while it was unusual for adult women to wear their pants (termed sokgot) without a covering skirt. As in Europe, a wide variety of styles came to define regions, time periods and age and gender groups, from the unlined gouei to the padded sombaji.^[35]

Women's trousers after 1900[edit]

Amazon wearing trousers and carrying a shield with an attached patterned cloth and a quiver. Ancient Greek Attic white-ground alabastron, ca. 470 BC, British Museum, London

Although women had been wearing trousers for outdoor work thousands of years earlier in the Western world, by the time of Christianization it had become taboo for women to wear trousers. It was Eastern culture that inspired French designer Paul Poiret (1879–1944) to be one of the first to design pants for women. In 1913 Poiret created loose-fitting, wide-leg trousers for women called harem pants, which were based on the costumes of the popular opera Sheherazade. Written by Nikola Rimsky-Korsakov in 1888, Sheherazade was based on a collection of legends from the Middle East called 1001 Arabian Nights.^[36]

In the early 20th century women air pilots and other working women often wore trousers. Frequent photographs from the 1930s of actressesMarlene Dietrich and Katharine Hepburn in trousers helped make trousers acceptable for women. During World War II, women working in factories and doing other forms of "men's work" on war service wore trousers when the work demanded it. In the post-war era, trousers became acceptable casual wear for gardening, the beach, and other leisurely pursuits. Further, in Britain during World War II, because of the rationing of clothing, many women took to wearing their husbands' civilian clothes, including their trousers, to work while their husbands were away from home serving in the armed forces. This was partly because they were seen as practical workwear and partly to allow women to keep their clothing allowance for other uses. As this practice of wearing trousers became more widespread and as the men's clothing wore out, replacements were needed. By the summer of 1944, it was reported that sales of women's trousers were five times more than they had been in the previous year.^[37]

In 1919, Luisa Capetillo challenged mainstream society by becoming the first woman in Puerto Rico to wear trousers in public. Capetillo was sent to jail for what was then considered to be a crime, but, the judge later dropped the charges against her.

In the 1960s, André Courrèges introduced long trousers for women as a fashion item, leading to the era of the pantsuit and designer jeans and the gradual erosion of social prohibitions against girls and women wearing trousers in schools, the workplace and in fine restaurants.

In 1969 Rep. Charlotte Reid (R-Ill.) became the first woman to wear trousers in the US Congress.^[38]

In 1989 California state senator Rebecca Morgan became the first woman to wear trousers in a US state senate.^[39]

Hillary Clinton was the first woman to wear trousers in an official U.S. First Lady portrait. ^[40]

Women were not allowed to wear trousers on the U.S. Senate floor until 1993. ^[41] ^[42] In 1993, Senators Barbara Mikulski and Carol Moseley Braun wore trousers onto the floor in defiance of the rule, and female support staff followed soon after, with the rule being amended later that year by Senate Sergeant-at-Arms Martha Pope to allow women to wear trousers on the floor so long as they also wore a jacket. ^[43] ^[44]

In Malawi women were not legally allowed to wear trousers under President Kamuzu Banda's rule until 1994.^[45] This law was introduced in 1965.^[46]

In 2009 journalist Lubna Hussein was fined the equivalent of $200 when a court found her guilty of violating Sudan's decency laws by wearing trousers.^[47]

In 2012 the Royal Canadian Mounted Police began to allow women to wear trousers and boots with all their formal uniforms. ^[48]

In 2012 and 2013, some Mormon women participated in "Wear Pants to Church Day," in which they wore trousers to church instead of the customary dresses to encourage gender equality within The Church of Jesus Christ of Latter-day Saints.^[49] ^[50] Over one thousand women participated in this in 2012. ^[51]

In 2013, Turkey's parliament ended a ban on women lawmakers wearing trousers in its assembly.^[52]

Also in 2013, an old bylaw requiring women in Paris, France to ask permission from city authorities before "dressing as men", including wearing trousers (with exceptions for those "holding a bicycle handlebar or the reins of a horse") was declared officially revoked by France's Women's Rights Minister, Najat Vallaud-Belkacem. ^[53] The bylaw was originally intended to prevent women from wearing the pantalons fashionable with Parisian rebels in the French Revolution.^[53]

Parts of trousers[edit]

Parts of trousers

Pleats[edit]

Pleats just below the waistband on the front typify many styles of formal and casual trousers, including suit trousers and khakis. There may be one, two, three, or no pleats, which may face either direction. When the pleats open towards the pockets they are called reverse pleats (typical of most trousers today) and when they open toward the fly they are known as forward pleats.

Cuffs[edit]

Trouser-makers can finish the legs by hemming the bottom to prevent fraying.^{[citation needed]} Trousers with turn-ups (cuffs in American English), after hemming, are rolled outward and sometimes pressed or stitched into place. The main reason for the turn-ups is to add weight to the bottom of the leg, to help the drape of the trousers.^{[original research?]}

Fly[edit]

Main article: Fly (clothing)

A fly is a covering over an opening join concealing the mechanism, such as a zipper, velcro or buttons, used to join the opening. In trousers, this is most commonly an opening covering the groin, which makes the pants easier to put on or take off. The opening also allows men to urinate without lowering their pants.

Trousers have varied historically in whether or not they have a fly. Originally, hose did not cover the area between the legs. This was instead covered by a doublet or by acodpiece. When breeches were worn, during the Regency period for example, they were fall-fronted (or broad fall). Later, after trousers (pantaloons) were invented, the fly-front (split fall) emerged.^[54] The panelled front returned as a sporting option, such as in riding breeches, but is now hardly ever used, a fly being by far the most common fastening. Most flies now use a zipper, though button-fly pants such as Levi's 501 jeans continue to be available.

Trouser support[edit]

At present, most trousers are held up through the assistance of a belt which is passed through the belt loops on the waistband of the trousers. However, this was traditionally a style acceptable only for casual trousers and work trousers; suit trousers and formal trousers were suspended by the use of braces (suspenders in American English) attached to buttons located on the interior or exterior of the waistband. Today, this remains the preferred method of trouser support amongst adherents of classical British tailoring. Many men claim this method is more effective and more comfortable because it requires no cinching of the waist or periodic adjustment.

Society[edit]

In modern Western society, males customarily wear trousers and not skirts or dresses. There are exceptions, however, such as the ceremonial Scottish kilt and Greek fustanella, as well as robes or robe-like clothing like the cassocks of clergy and the academic robes, both rarely worn today in daily use. (See also Men's skirts.)

Convertible Ventilated Trousers shown with one leg cover removed

Based on Deuteronomy 22:5 in the Bible ("The woman shall not wear that which pertaineth unto a man"), some groups, including the Amish, Hutterites, some Mennonites, some Baptists, a few Church of Christ groups, and most Orthodox Jews, believe that women should not weartrousers, but only skirts and dresses. These groups do permit women to wear underpants as long as they are hidden. By contrast, many Muslim sects approve of pants as they are considered more modest than any skirt that is shorter than ankle length.

Among certain groups, low-rise, baggy trousers exposing underwear became fashionable; for example, among skaters and in 1990s hip hop fashion. This fashion is called sagging or, alternatively, "busting slack."^[55]

Cut-offs are homemade shorts made by cutting the legs off trousers, usually after holes have been worn in fabric around the knees. This extends the useful life of the trousers. The remaining leg fabric may be hemmed or left to fray after being cut.

Laws[edit]

France[edit]

In 2013, a bylaw requiring women in Paris, France to ask permission from city authorities before "dressing as men", including wearing trousers (with exceptions for those "holding a bicycle handlebar or the reins of a horse") was declared officially revoked by France's Women's Rights Minister, Najat Vallaud-Belkacem. ^[53] The bylaw was originally intended to prevent women from wearing the pantalons fashionable with Parisian rebels in the French Revolution.^[53]

Malawi[edit]

In Malawi women were not legally allowed to wear trousers under President Kamuzu Banda's rule until 1994.^[45] This law was introduced in 1965.^[46]

Puerto Rico[edit]

Turkey[edit]

In 2013, Turkey's parliament ended a ban on women lawmakers wearing trousers in its assembly.^[52]

Sudan[edit]

In Sudan, Article 152 of the Memorandum to the 1991 Penal Code prohibits the wearing of "obscene outfits" in public. This law has been used to arrest and prosecute women wearing trousers. Thirteen women including journalist Lubna al-Hussein were arrested in Khartoum in July 2009 for wearing trousers; ten of the women pleaded guilty and were flogged with ten lashes and fined 250 Sudanese pounds apiece. Lubna al-Hussein considers herself a good Muslim and asserts "Islam does not say whether a woman can wear trousers or not. I'm not afraid of being flogged. It doesn't hurt. But it is insulting." She was eventually found guilty and fined the equivalent of $200 rather than being flogged. ^[56]

USA[edit]

In May 2004, in Louisiana, Democrat and state legislator Derrick Shepherd proposed a bill that would make it a crime to appear in public wearing trousers below the waist and thereby exposing one's skin or "intimate clothing".^[57] The Louisiana bill did not pass.

In February 2005, Virginia legislators tried to pass a similar law that would have made punishable by a $50 fine "any person who, while in a public place, intentionally wears and displays his below-waist undergarments, intended to cover a person's intimate parts, in a lewd or indecent manner". (It is not clear whether, with the same coverage by the trousers, exposing underwear was considered worse than exposing bare skin, or whether the latter was already covered by another law.) The law passed in the Virginia House of Delegates. However, various criticisms to it arose. For example, newspaper columnists and radio talk show hosts consistently said that since most people that would be penalized under the law would be young African-American men, the law would thus be a form of racial discrimination. Virginia's state senators voted against passing the law.^[58]^[59]

In California, Government Code Section 12947.5 (part of the California Fair Employment and Housing Act (FEHA)) expressly protects the right to wear pants (American Englishfor trousers).^[60] Thus, the standard California FEHA discrimination complaint form includes an option for "denied the right to wear pants."

The History of Panipuri

2014-11-01T02:59:00.003-07:00

Panipuri

Panipuri

Alternative names	Pani Ke Patashe, Phuchka, Gup Chup, Paani Poori, Pani ke Bataashe, Pakodi, Gol GappA, Ghopcha.
Type	Snack
Place of origin	India and Nepal
Region or state	India, Nepal, Bangladesh
Main ingredients	Flour, spiced water, onions,potatoes, chickpeas
Cookbook:Panipuri Panipuri

The Panipuri ( pānīpūrī (help·info), Nepali: पानीपूरी, also known as Gol gappa, Urdu: گول گپّے‎, pani ke bataashe,Marathi: पाणीपुरी,Gujarati: પાણી પુરી, term used in Western India, phuchka (Bengali: ফুচকা), or gup chup (Oriya: ଗୁପଚୁପ୍)) is a popular street snack inIndia, Pakistan, Bangladesh, and Nepal. It consists of a round, hollow puri, fried crisp and filled with a mixture of flavored water ("pani"),tamarind chutney, chili, chaat masala, potato, onion and chickpeas. It is generally small enough to fit completely into one's mouth. It is a popular street food dish in Mumbai, Kolkata, Delhi, Lucknow, Karachi, Lahore, Chittagong, Dhaka and Kathmandu.

In North India it is known as Gol Gappa. The name 'gol gappa' refers to the crisp sphere (gol) that is placed in the mouth and eaten (gappa) one at a time. Pani comes from the Hindi word for water and puri (or poori) is the name of an Indian bread made by deep frying in oil. Dogras, Kashmiris, Bhaderwahis, Gujjars, Paharis, Ladakhis, Himachalis of North India called it "Gol Gappa'. It is known asbataasha in the Western region of Uttar Pradesh. Bataasha is something which gets smashed with application of a slight pressure; the bataasha gets smashed as soon as it is placed inside the mouth. It is known as Phuchka in Eastern Indian states like Bihar, Jharkhandand West Bengal, also in Bangladesh. Because of the bursting sound in the mouth when it is eaten, called gup chup inOdisha,Hyderabad and South Jharkhand. Gol-Gappa or Pani Pataase in Madhya Pradesh, Gup-Chup or Gol-Gappa or Panipuri inChhattisgarh. In several parts of Gujarat and Kutch. It is commonly known as pakodi (પકોડી), not to be confused with pakoda.

History[edit]

The panipuri originated from the Magadha region of India, present day South Bihar where it is also known as phulki. The English meaning of golgappa is "watery bread" or "crisp sphere eaten." The literal meaning suggests that it may have originated from Varanasi.^[1]^[2] In Bengal and specifically Kolkata, Phuchka is considered to be the king of this variety of snacks, compared to its cousins like golgappas or panipuris. The filling is made by lightly mashing boiled potatoes with black salt, salt, some spices, a generous portion of tamarind pulp (made by mashing ripe tamarind in tamarind water), chilli (powder/chopped/boiled & pasted). The tamarind water Tetul Jol is made by mixing tamarind and spices/ salt and making a light and tart liquid with water. At some places like Deshpriya Park, a very famous variety is made with sour curd, and called Dahi (curd) Phuchka.

Names[edit]

Its popular names and the area where it is known by this name are:

Name	Region
Pani Ke Patashe	Haryana
Gol Gappa	West Bengal, New Delhi, Punjab, Jammu & Kashmir, Haryana, Jharkhand, Bihar, Madhya Pradesh and Himachal Pradesh in India; almost everywhere in Pakistan
Pani ke bataashe / Patashi	Rajasthan, Uttar Pradesh
Panipuri	Hilly part of neighbouring country Nepal, Maharashtra (Mumbai and all the parts of Maharashtra), Madhya Pradesh, Gujarat, Karnataka, Tamil Nadu
Phuchka	West Bengal, Assam (India) and Bangladesh
Gup chup	West Bengal,Odisha, South Jharkhand, Chhatisgarh, Hyderabad, Telangana
Pakodi	Gujarat (some parts)
Phulki	Terai Part in Nepal, Madhya Pradesh
Tikki	Hoshangabad (Madhya Pradesh)
Padaka	Aligarh (Uttar Pradesh)
Phulki	Mirzapur (Uttar Pradesh)

Presentation[edit]

Panipuri

Home made Panipuri.

Panipuri stall

A plate of Pakistani gol gappas (centre) accompanied with other foods

It all depends on an individual's choice to present panipuris in their own way. One may find different flavors and ingredients involved, but the basic shape, size and its effect remains almost same.

Typically, 4–8 panipuris are served over a portion on a triangular plate made from dry sal leaves. Some places offer panipuris prepared on a whole plate, but the popular way for them to be served is one-at-a-time from a roadside vendor. Customers hold a small plate or bowl (katori) and stand around the vendors cart. The server then starts making one panipuri at a time and gives one to each individual. Panipuri servers have to remember each customer's preferences such as sweetened pani, more filling or extra onions, for example. The server must keep count of how many panipuris each person has had.

Traditionally, panipuris are eaten by placing the entire puri into the mouth in one go and biting into it. This releases a barrage of tastes and textures. Panipuris may be finished off with a cup of the pani, sweetened or made tarter to taste.

Variations[edit]

While many regions in India have their own variations of the panipuri, the most famous ones are from Kolkata, called 'Phuchka'.^[3]

In Lucknow, this dish is known as "Pani ke bataashe", which means a crispy round dish having spicy water inside. A hole is made using a thumb in the "Bataasha" and a small amount of boiled peas is filled inside it and then the "Bataasha" is dipped in the spicy water or "Pani". In the Lucknow region the Pani is prepared using mint, tamarind, asafoetida (hing), black pepper, red chili powder and salt. At Hazratganj in Lucknow you can savour Paanch Swaad Ke bataashe which means the bataashe are served with five differently tasting Pani one after another.

In most parts of India, a panipuri is made with flavoured water. Some examples are imli ka pani (tamarind in water), nimbu ka pani (lemon juice in water), pudine ka pani (mint in water) and khajur ka pani (dates mixed in water). In West Bengal, Odisha, Mithilanchal part of Bihar and the southern part of Jharkhand, many people enjoy panipuris containing no sweet but with tamarind juice and spicy mashed potato.

In parts of Bihar, however it is also served along with "patta chat" comprising khesiya dried channa Black gram (Kala Chana) or dried yellow peas coated with hot freshly grinded green masalas recipe for which is basically dried black, yellow or green Bengal gram that is soaked in water for a minute and then washed in running water immediately and put in a frying pan/kardahi with shallow filled with mustard oil reaching smoky point preferably cooked in Chinese wok style, and the moment it starts giving/releasing pleasant sweet smell/scent/aroma/odour/fragrance/parfumes then add the dry green masalas comprising onion, garlic, ginger, green chilli, black & red pepper powder {curry leaves & a pinch of asfoetida optional} grounded/pounded in the puree/paste form in the rough style once the spices are evenly mixed remove it from flame let it cool, this can be stored as snacks too for up to a month. Alternatively, this at times is replaced with Ghugaenialias Ghoogini. It is then served with muri (sometimes spelled mouri)(mur-mure/kurmura/churmura or Muhdhi), and at times with hot onion pakoda/bonda or Uggani/Goli Baje/Wadaieyan Batata vada/ambode/Maddur vade/Sabudana vada style bhajiya Fritter of dried chick peasdumplings made up with onion slices/julienned with grated green chilli & potato or garlic. Make small balls with this mixture (a little smaller than a golf ball), flatten them a bit, and set aside. Fry these flattened pieces in the smoky hot oil, until they turn golden brown. Then, put it in diluted watery gravy in garam masala seasoning and cooked in cverd lid just ot make them tender for a while, in the traditional eastern Indian style & thereafter, kachalou is prepared with par-boiled blanch-cooked peeled potatoes are cut in slices, cubes or crumbled with sour hung/thick curd and mixed with chat masala & jeera namak (grounded black rock salt along with roasted cumin seeds, white & red pepper powder apportioned and mixed in 3:2:1 ratio) in a very pungent manner and then diluted with (dried mango powder)amchoor/tamarind & pudina/dhaniya water as per own taste bud. These all go very well as a filling in the Pani Puri.

In Jamshedpur, a mixture of hot "chole" made of yellow peas, boiled smashed potato, lots of fresh onion pieces, green chillies, tamarind juice and spices are mixed to make stuffing for golgappe. There are two types of golguppe: with tamarind water (a.k.a. phulki) or dry (aka; papadi).

One needs to break open the golgappe and stuff the mixture into it and put tamarind water in it. Papadi are those golgappe which are mostly flat. All the stuffing goes on the top of the papadi.

In Maharashtra, by contrast, the recipe is usually spicier and contains boondi or sprouts in addition to other ingredients. Panipuris are also eaten with curd and different types of masalas such as onion, sev (a type of besan vermicelli without any spices & seasoning)|(a fried snack shaped like thin noodles made from besan flour), and mixture (a mix of different types of fried snacks mixed together) or Bhujia along with available seasonal nuts, as the base of the snack. As we go down south India pani puri has taken its own variations in many regions. Hyderabad is famous for panipuri in Andhra Pradesh. Here the road side stalls serve pani puris with Boiled Chickpeas filled accompanied by spicy pani. At times the boiled chick peas is again warmed upon the tava with the addition of few more spices to this and is filled into the puris. These are lighter when compared to the potato stuffing.

In Bangalore the phuchka version of panipuris are served on streets with raw onions added.

The panipuri is also an off-beat recent entrant delicacy in northeastern as well in southern part of India popularized by Bollywood movies and the heavy influence following of neighbouring Northern Indian states traditions of cuisine cultural potpourri. It is blamed for an increase on stomach ache there. In Bengal, ingredients add chili powder, coriander powder, turmeric powder, salt, spicy fish curry ras along with saute ginger, garlic, green chilies. .

Cultural references[edit]

A monthly children's magazine, Golgappa, was published from 1970 in Delhi.^[4] They were used in the Hindi movie Rab Ne Bana Di Jodi, starring Shahrukh Khan & Anushka Sharma, in one scene called the "Gol Gappe Challenge." The person who ate the most is the winner, and the person who ate the least is the loser. The loser had to do anything the winner wanted from her or him. There is also an old song, still used till now, called "Gol Gappe Wala Aaya" (English: The Gol Gappe Man Is Here).

Nutritional information[edit]

Golgappas are generally considered to be a popular low calorie snack (typical serving size being 4 golgappas). The nutritional information per typical un-stuffed suji golgappa is (approximately 12g^{[citation needed]})

Nutrient	Weight
Fats	3 g
Carbohydrates	4 g
Protein	1 g

Calorie information for the golgappa (12g unstuffed) would be:

Calories from Fats	27 Kcal
Calories from Carbohydrates	16 Kcal
Calories from Protein	04 Kcal

The History of Antenna (Radio)

2014-10-20T20:21:00.003-07:00

Antenna (radio)

Antennas
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An antenna (or aerial) is an electrical device which converts electric power into radio waves, and vice versa.^[1] It is usually used with aradio transmitter or radio receiver. In transmission, a radio transmitter supplies an electric current oscillating at radio frequency (i.e. a high frequency alternating current (AC)) to the antenna's terminals, and the antenna radiates the energy from the current aselectromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified.

Antennas are essential components of all equipment that uses radio. They are used in systems such as radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, and satellite communications, as well as other devices such asgarage door openers, wireless microphones, Bluetooth-enabled devices, wireless computer networks, baby monitors, and RFID tags on merchandise.

Typically an antenna consists of an arrangement of metallic conductors (elements), electrically connected (often through a transmission line) to the receiver or transmitter. An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements. These time-varying fields radiate away from the antenna into space as a moving transverse electromagnetic field wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.

Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional or high gain antennas). In the latter case, an antenna may also include additional elements or surfaces with no electrical connection to the transmitter or receiver, such as parasitic elements, parabolic reflectors or horns, which serve to direct the radio waves into a beam or other desired radiation pattern.

The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory ofJames Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving. He published his work in Annalen der Physik und Chemie (vol. 36, 1889).

Terminology[edit]

Electronic symbol for an antenna

The words antenna (plural: antennas^[2] in US English, although both "antennas" and "antennae" are used in International English^[3]) and aerial are used interchangeably. Occasionally a rigid metallic structure is called an "antenna" while the wire form is called an "aerial". However, note the important internationaltechnical journal, the IEEE Transactions on Antennas and Propagation.^[4] In the United Kingdom and other areas where British English is used, the term aerial is sometimes used although 'antenna' has been universal in professional use for many years.

The origin of the word antenna relative to wireless apparatus is attributed to Italian radio pioneer Guglielmo Marconi. In 1895, while testing early radio apparatus in the Swiss Alps at Salvan, Switzerland in the Mont Blanc region, Marconi experimented with long wire "aerials". He used a 2.5 meter vertical pole, with a wire attached to the top running down to the transmitter, as a radiating and receiving aerial element. In Italian a tent pole is known as l'antenna centrale, and the pole with the wire was simply called l'antenna. Until then wireless radiating transmitting and receiving elements were known simply as aerials or terminals. Because of his prominence, Marconi's use of the word antenna (Italian for pole) spread among wireless researchers,^[5]^[6]^[7] and later to the general public.^[8]

In common usage, the word antenna may refer broadly to an entire assembly including support structure, enclosure (if any), etc. in addition to the actual functional components. Especially at microwave frequencies, a receiving antenna may include not only the actual electrical antenna but an integrated preamplifier or mixer.

Overview[edit]

Antennas are required by any radio receiver or transmitter to couple its electrical connection to the electromagnetic field. Radio waves areelectromagnetic waves which carry signals through the air (or through space) at the speed of light with almost no transmission loss. Radio transmitters and receivers are used to convey signals (information) in systems including broadcast (audio) radio, television, mobile telephones, Wi-Fi (WLAN) data networks, trunk lines and point-to-point communications links (telephone, data networks), satellite links, manyremote controlled devices such as garage door openers, and wireless remote sensors, among many others. Radio waves are also used directly for measurements in technologies including radar, GPS, and radio astronomy. In each and every case, the transmitters and receivers involved require antennas, although these are sometimes hidden (such as the antenna inside an AM radio or inside a laptop computer equipped with Wi-Fi).

Antennas of the Atacama Large Millimeter submillimeter Array.^[9]

Whip antenna on car, common example of an omnidirectional antenna

According to their applications and technology available, antennas generally fall in one of two categories:

Omnidirectional or only weakly directional antennas which receive or radiate more or less in all directions. These are employed when the relative position of the other station is unknown or arbitrary. They are also used at lower frequencies where a directional antenna would be too large, or simply to cut costs in applications where a directional antenna isn't required.
Directional or beam antennas which are intended to preferentially radiate or receive in a particular direction or directional pattern.

In common usage "omnidirectional" usually refers to all horizontal directions, typically with reduced performance in the direction of the sky or the ground (a truly isotropic radiator is not even possible). A "directional" antenna usually is intended to maximize its coupling to the electromagnetic field in the direction of the other station, or sometimes to cover a particular sector such as a 120° horizontal fan pattern in the case of a panel antenna at a cell site.

One example of omnidirectional antennas is the very common vertical antenna or whip antenna consisting of a metal rod (often, but not always, a quarter of a wavelength long). A dipole antenna is similar but consists of two such conductors extending in opposite directions, with a total length that is often, but not always, a half of a wavelength long. Dipoles are typically oriented horizontally in which case they are weakly directional: signals are reasonably well radiated toward or received from all directions with the exception of the direction along the conductor itself; this region is called the antenna blind cone or null.

Half-wave dipole antenna

Both the vertical and dipole antennas are simple in construction and relatively inexpensive. The dipole antenna, which is the basis for most antenna designs, is a balanced component, with equal but opposite voltages and currents applied at its two terminals through a balanced transmission line (or to a coaxial transmission line through a so-called balun). The vertical antenna, on the other hand, is a monopole antenna. It is typically connected to the inner conductor of a coaxial transmission line (or a matching network); the shield of the transmission line is connected to ground. In this way, the ground (or any large conductive surface) plays the role of the second conductor of a dipole, thereby forming a complete circuit. Since monopole antennas rely on a conductive ground, a so-called grounding structure may be employed to provide a better ground contact to the earth or which itself acts as a ground plane to perform that function regardless of (or in absence of) an actual contact with the earth.

Diagram of the electric fields (blue) and magnetic fields (red) radiated by adipole antenna (black rods) during transmission.

Antennas more complex than the dipole or vertical designs are usually intended to increase the directivity and consequently the gain of the antenna. This can be accomplished in many different ways leading to a plethora of antenna designs. The vast majority of designs are fed with a balanced line (unlike a monopole antenna) and are based on the dipole antenna with additional components (orelements) which increase its directionality. Antenna "gain" in this instance describes the concentration of radiated power into a particular solid angle of space, as opposed to the spherically uniform radiation of the ideal radiator. The increased power in the desired direction is at the expense of that in the undesired directions. Power is conserved, and there is no net power increase over that delivered from the power source (the transmitter.)

For instance, a phased array consists of two or more simple antennas which are connected together through an electrical network. This often involves a number of parallel dipole antennas with a certain spacing. Depending on the relative phase introduced by the network, the same combination of dipole antennas can operate as a "broadside array" (directional normal to a line connecting the elements) or as an "end-fire array" (directional along the line connecting the elements). Antenna arrays may employ any basic (omnidirectional or weakly directional) antenna type, such as dipole, loop or slot antennas. These elements are often identical.

Rooftop televisionYagi-Uda antennas like these six are widely used at VHF and UHFfrequencies.

However a log-periodic dipole array consists of a number of dipole elements of different lengths in order to obtain a somewhat directional antenna having an extremely wide bandwidth: these are frequently used for television reception in fringe areas. The dipole antennas composing it are all considered "active elements" since they are all electrically connected together (and to the transmission line). On the other hand, a superficially similar dipole array, the Yagi-Uda Antenna (or simply "Yagi"), has only one dipole element with an electrical connection; the other so-called parasitic elementsinteract with the electromagnetic field in order to realize a fairly directional antenna but one which is limited to a rather narrow bandwidth. The Yagi antenna has similar looking parasitic dipole elements but which act differently due to their somewhat different lengths. There may be a number of so-called "directors" in front of the active element in the direction of propagation, and usually a single (but possibly more) "reflector" on the opposite side of the active element.

Greater directionality can be obtained using beam-forming techniques such as a parabolic reflector or a horn. Since the size of a directional antenna depends on it being large compared to the wavelength, very directional antennas of this sort are mainly feasible at UHF and microwave frequencies. On the other hand, at low frequencies (such as AM broadcast) where a practical antenna must be much smaller than a wavelength, significant directionality isn't even possible. A vertical antenna or loop antenna small compared to the wavelength is typically used, with the main design challenge being that ofimpedance matching. With a vertical antenna a loading coil at the base of the antenna may be employed to cancel the reactive component of impedance; small loop antennas are tuned with parallel capacitors for this purpose.

An antenna lead-in is the transmission line (or feed line) which connects the antenna to a transmitter or receiver. The antenna feed may refer to all components connecting the antenna to the transmitter or receiver, such as an impedance matching network in addition to the transmission line. In a so-called aperture antenna, such as a horn or parabolic dish, the "feed" may also refer to a basic antenna inside the entire system (normally at the focus of the parabolic dish or at the throat of a horn) which could be considered the one active element in that antenna system. A microwave antenna may also be fed directly from a waveguide in lieu of a (conductive) transmission line.

Cell phone base station antennas

An antenna counterpoise or ground plane is a structure of conductive material which improves or substitutes for the ground. It may be connected to or insulated from the natural ground. In a monopole antenna, this aids in the function of the natural ground, particularly where variations (or limitations) of the characteristics of the natural ground interfere with its proper function. Such a structure is normally connected to the return connection of an unbalanced transmission line such as the shield of a coaxial cable.

An electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative to the other side. It can, for instance, bring the wave to a focus or alter the wave front in other ways, generally in order to maximize the directivity of the antenna system. This is the radio equivalent of an optical lens.

An antenna coupling network is a passive network (generally a combination of inductive and capacitive circuit elements) used for impedance matching in between the antenna and the transmitter or receiver. This may be used to improve the standing wave ratio in order to minimize losses in the transmission line and to present the transmitter or receiver with a standard resistive impedance that it expects to see for optimum operation.

Reciprocity[edit]

It is a fundamental property of antennas that the electrical characteristics of an antenna described in the next section, such as gain, radiation pattern, impedance, bandwidth,resonant frequency and polarization, are the same whether the antenna is transmitting or receiving.^[10]^[11] For example, the "receiving pattern" (sensitivity as a function of direction) of an antenna when used for reception is identical to the radiation pattern of the antenna when it is driven and functions as a radiator. This is a consequence of the reciprocity theoremof electromagnetics.^[11] Therefore in discussions of antenna properties no distinction is usually made between receiving and transmitting terminology, and the antenna can be viewed as either transmitting or receiving, whichever is more convenient.

A necessary condition for the aforementioned reciprocity property is that the materials in the antenna and transmission medium are linear and reciprocal. Reciprocal (or bilateral) means that the material has the same response to an electric current or magnetic field in one direction, as it has to the field or current in the opposite direction. Most materials used in antennas meet these conditions, but some microwave antennas use high-tech components such as isolators and circulators, made of nonreciprocal materials such as ferrite.^[10]^[11]These can be used to give the antenna a different behavior on receiving than it has on transmitting,^[10] which can be useful in applications like radar.

Characteristics[edit]

Antennas are characterized by a number of performance measures which a user would be concerned with in selecting or designing an antenna for a particular application. Chief among these relate to the directional characteristics (as depicted in the antenna's radiation pattern) and the resulting gain. Even in omnidirectional (or weakly directional) antennas, the gain can often be increased by concentrating more of its power in the horizontal directions, sacrificing power radiated toward the sky and ground. The antenna's power gain (or simply "gain") also takes into account the antenna's efficiency, and is often the primary figure of merit.See also: Antenna measurement

Resonant antennas are expected to be used around a particular resonant frequency; an antenna must therefore be built or ordered to match the frequency range of the intended application. A particular antenna design will present a particular feedpoint impedance. While this may affect the choice of an antenna, an antenna's impedance can also be adapted to the desired impedance level of a system using a matching network while maintaining the other characteristics (except for a possible loss of efficiency).

Although these parameters can be measured in principle, such measurements are difficult and require very specialized equipment. Beyond tuning a transmitting antenna using anSWR meter, the typical user will depend on theoretical predictions based on the antenna design or on claims of a vendor.

An antenna transmits and receives radio waves with a particular polarization which can be reoriented by tilting the axis of the antenna in many (but not all) cases. The physical size of an antenna is often a practical issue, particularly at lower frequencies (longer wavelengths). Highly directional antennas need to be significantly larger than the wavelength. Resonant antennas usually use a linear conductor (or element), or pair of such elements, each of which is about a quarter of the wavelength in length (an odd multiple of quarter wavelengths will also be resonant). Antennas that are required to be small compared to the wavelength sacrifice efficiency and cannot be very directional. Fortunately at higher frequencies (UHF, microwaves) trading off performance to obtain a smaller physical size is usually not required.

Resonant antennas[edit]

While there are broadband designs for antennas, the vast majority of antennas are based on the half-wave dipole which has a particular resonant frequency. At its resonant frequency, the wavelength (figured by dividing the speed of light by the resonant frequency) is slightly over twice the length of the half-wave dipole (thus the name). The quarter-wave vertical antenna consists of one arm of a half-wave dipole, with the other arm replaced by a connection to ground or an equivalent ground plane (or counterpoise). A Yagi-Uda array consists of a number of resonant dipole elements, only one of which is directly connected to the transmission line. The quarter-wave elements of a dipole or vertical monopole imitate a series-resonant electrical element due to the standing wave present along the conductor. At the resonant frequency, the standing wave has a current peak and voltage node (minimum) at the feed-point, thus presenting a lower impedance than at other frequencies. What's more, the large current and small voltage are in phase at that point, resulting in a purely resistive impedance, whereas away from the design frequency the feed-point impedance both rises and becomes reactive. Contrary to an ideal (lossless) series-resonant circuit, a finite resistance remains (corresponding to the relatively small voltage at the feed-point) due to the antenna's radiation resistance (as well as any actual electrical losses).

A common misconception is that the ability of a resonant antenna to transmit (or receive) fails at frequencies far from the resonant frequency. The reason a dipole antenna needs to be used at the resonant frequency has to do with the impedance match between the antenna and the transmitter or receiver (and its transmission line). For instance, a dipole using a fairly thin conductor^[12] will have a purely resistive feedpoint impedance of about 63 ohms at its design frequency. Feeding that antenna with a current of 1 ampere will require 63 volts of RF, and the antenna will radiate 63 watts (ignoring losses) of radio frequency power. If that antenna is driven with 1 ampere at a frequency 20% higher, it will still radiate as efficiently but in order to do that about 200 volts would be required due to the change in the antenna's impedance which is now largely reactive (voltage out of phase with the current). A typical transmitter would not find that impedance acceptable and would deliver much less than 63 watts to it; the transmission line would be operating at a high (poor)standing wave ratio. But using an appropriate matching network, that large reactive impedance could be converted to a resistive impedance satisfying the transmitter and accepting the available power of the transmitter.

This principle is used to construct vertical antennas substantially shorter than the 1/4 wavelength at which the antenna is resonant. By adding an inductance in series with the vertical antenna (a so-called loading coil) the capacitive reactance of this antenna can be cancelled leaving a pure resistance which can then be matched to the transmission line. Sometimes the resulting resonant frequency of such a system (antenna plus matching network) is described using the construct of "electrical length" and the use of a shorter antenna at a lower frequency than its resonant frequency is termed "electrical lengthening". For example, at 30 MHz (wavelength = 10 meters) a true resonant monopole would be almost 2.5 meters (1/4 wavelength) long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has "lengthened" the antenna to achieve an "electrical length" of 2.5 meters, that is, 1/4 wavelength at 30 MHz where the combined system now resonates. However, the resulting resistive impedance achieved will be quite a bit lower than the impedance of a resonant monopole, likely requiring further impedance matching. In addition to a lower radiation resistance, the reactance becomes higher as the antenna size is reduced, and the resonant circuit formed by the antenna and the tuning coil has a Q factor that rises and eventually causes the bandwidth of the antenna to be inadequate for the signal being transmitted. This is the major factor that sets the size of antennas at 1 MHz and lower frequencies.

Current and voltage distribution[edit]

The antenna conductors have the lowest feed-point impedance at the resonant frequency where they are just under 1/4 wavelength long; two such conductors in line fed differentially thus realizes the familiar "half-wave dipole". When fed with an RF current at the resonant frequency, the quarter wave element contains a standing wave with the voltage and current largely (but not exactly) in phase quadrature, as would be obtained using a quarter wave stub of transmission line. The current reaches a minimum at the end of the element (where it has nowhere to go!) and is maximum at the feed-point. The voltage, on the other hand, is the greatest at the end of the conductor and reaches a minimum (but not zero) at the feedpoint. Making the conductor shorter or longer than 1/4 wavelength means that the voltage pattern reaches its minimum somewhere beyond the feed-point, so that the feed-point has a higher voltage and thus sees a higher impedance, as we have noted. Since that voltage pattern is almost in phase quadrature with the current, the impedance seen at the feed-point is not only much higher but mainly reactive.

It can be seen that if such an element is resonant at f₀ to produce such a standing wave pattern, then feeding that element with 3f₀ (whose wavelength is 1/3 that of f₀) will lead to a standing wave pattern in which the voltage is likewise a minimum at the feed-point (and the current at a maximum there). Thus, an antenna element is also resonant when its length is 3/4 of a wavelength (3/2 wavelength for a complete dipole). This is true for all odd multiples of 1/4 wavelength, where the feed-point impedance is purely resistive, though larger than the resistive impedance of the 1/4 wave element. Although such an antenna is resonant and works perfectly well at the higher frequency, the antenna radiation pattern is also altered compared to the half-wave dipole.

The use of a monopole or dipole at odd multiples of the fundamental resonant frequency, however, does not extend to even multiples (thus a 1/2 wavelength monopole or 1 wavelength dipole). Now the voltage standing wave is at its peak at the feed-point, while that of the current (which must be zero at the end of the conductor) is at a minimum (but not exactly zero). The antenna is anti-resonant at this frequency. Although the reactance at the feedpoint can be cancelled using such an element length, the feed-point impedance is very high, and is highly dependent on the diameter of the conductor (which makes only a small difference at the actual resonant frequency). Such an antenna does not match the much lower characteristic impedance of available transmission lines, and is generally not used. However some equipment where transmission lines are not involved which desire a high driving point impedance may take advantage of this anti-resonance.

Bandwidth[edit]

Although a resonant antenna has a purely resistive feed-point impedance at a particular frequency, many (if not most) applications require using an antenna over a range of frequencies. An antenna's bandwidth specifies the range of frequencies over which its performance does not suffer due to a poor impedance match. Also in the case of a Yagi-Udaarray, the use of the antenna very far away from its design frequency reduces the antenna's directivity, thus reducing the usable bandwidth regardless of impedance matching.

Except for the latter concern, the resonant frequency of a resonant antenna can always be altered by adjusting a suitable matching network. To do this efficiently one would require remotely adjusting a matching network at the site of the antenna, since simply adjusting a matching network at the transmitter (or receiver) would leave the transmission line with a poor standing wave ratio.

Instead, it is often desired to have an antenna whose impedance does not vary so greatly over a certain bandwidth. It turns out that the amount of reactance seen at the terminals of a resonant antenna when the frequency is shifted, say, by 5%, depends very much on the diameter of the conductor used. A long thin wire used as a half-wave dipole (or quarter wave monopole) will have a reactance significantly greater than the resistive impedance it has at resonance, leading to a poor match and generally unacceptable performance. Making the element using a tube of a diameter perhaps 1/50 of its length, however, results in a reactance at this altered frequency which is not so great, and a much less serious mismatch which will only modestly damage the antenna's net performance. Thus rather thick tubes are typically used for the solid elements of such antennas, including Yagi-Uda arrays.

Rather than just using a thick tube, there are similar techniques used to the same effect such as replacing thin wire elements with cages to simulate a thicker element. This widens the bandwidth of the resonance. On the other hand, amateur radio antennas need to operate over several bands which are widely separated from each other. This can often be accomplished simply by connecting resonant elements for the different bands in parallel. Most of the transmitter's power will flow into the resonant element while the others present a high (reactive) impedance and draw little current from the same voltage. A popular solution uses so-called traps consisting of parallel resonant circuits which are strategically placed in breaks along each antenna element. When used at one particular frequency band the trap presents a very high impedance (parallel resonance) effectively truncating the element at that length, making it a proper resonant antenna. At a lower frequency the trap allows the full length of the element to be employed, albeit with a shifted resonant frequency due to the inclusion of the trap's net reactance at that lower frequency.

The bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for "quality factor" and a low Q typically signifies excessive loss (due to unwanted resistance) in a resonant L-C circuit. However this understanding does not apply to resonant antennas where the resistance involved is the radiation resistance, a desired quantity which removes energy from the resonant element in order to radiate it (the purpose of an antenna, after all!). The Q is a measure of the ratio of reactance to resistance, so with a fixed radiation resistance (an element's radiation resistance is almost independent of its diameter) a greater reactance off-resonance corresponds to the poorer bandwidth of a very thin conductor. The Q of such a narrowband antenna can be as high as 15. On the other hand a thick element presents less reactance at an off-resonant frequency, and consequently a Q as low as 5. These two antennas will perform equivalently at the resonant frequency, but the second antenna will perform over a bandwidth 3 times as wide as the "hi-Q" antenna consisting of a thin conductor.

Gain[edit]

Main article: Antenna gain

Gain is a parameter which measures the degree of directivity of the antenna's radiation pattern. A high-gain antenna will preferentially radiate in a particular direction. Specifically, theantenna gain, or power gain of an antenna is defined as the ratio of the intensity (power per unit surface) radiated by the antenna in the direction of its maximum output, at an arbitrary distance, divided by the intensity radiated at the same distance by a hypothetical isotropic antenna.

The gain of an antenna is a passive phenomenon - power is not added by the antenna, but simply redistributed to provide more radiated power in a certain direction than would be transmitted by an isotropic antenna. An antenna designer must take into account the application for the antenna when determining the gain. High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully in a particular direction. Low-gain antennas have shorter range, but the orientation of the antenna is relatively inconsequential. For example, a dish antenna on a spacecraft is a high-gain device that must be pointed at the planet to be effective, whereas a typical Wi-Fi antenna in a laptop computer is low-gain, and as long as the base station is within range, the antenna can be in any orientation in space. It makes sense to improve horizontal range at the expense of reception above or below the antenna.^[13]

In practice, the half-wave dipole is taken as a reference instead of the isotropic radiator. The gain is then given in dBd (decibels over dipole):

NOTE: 0 dBd = 2.15 dBi. It is vital in expressing gain values that the reference point be included. Failure to do so can lead to confusion and error.

Effective area or aperture[edit]

Main article: Antenna effective area

The effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m² (10⁻¹² watts per square meter) and an antenna has an effective area of 12 m², then the antenna would deliver 12 pW of RF power to the receiver (30 microvolts rms at 75 ohms). Since the receiving antenna is not equally sensitive to signals received from all directions, the effective area is a function of the direction to the source.

Due to reciprocity (discussed above) the gain of an antenna used for transmitting must be proportional to its effective area when used for receiving. Consider an antenna with no loss, that is, one whose electrical efficiency is 100%. It can be shown that its effective area averaged over all directions must be equal to λ²/4π, the wavelength squared divided by 4π. Gain is defined such that the average gain over all directions for an antenna with 100% electrical efficiency is equal to 1. Therefore the effective area A_eff in terms of the gain G in a given direction is given by:

For an antenna with an efficiency of less than 100%, both the effective area and gain are reduced by that same amount. Therefore the above relationship between gain and effective area still holds. These are thus two different ways of expressing the same quantity. A_eff is especially convenient when computing the power that would be received by an antenna of a specified gain, as illustrated by the above example.

Radiation pattern[edit]

Main article: Radiation pattern

Polar plots of the horizontal cross sections of a (virtual) Yagi-Uda-antenna. Outline connects points with 3db field power compared to an ISO emitter.

The radiation pattern of an antenna is a plot of the relative field strength of the radio waves emitted by the antenna at different angles. It is typically represented by a three-dimensional graph, or polar plots of the horizontal and vertical cross sections. The pattern of an idealisotropic antenna, which radiates equally in all directions, would look like a sphere. Many nondirectional antennas, such as monopoles anddipoles, emit equal power in all horizontal directions, with the power dropping off at higher and lower angles; this is called an omnidirectional pattern and when plotted looks like a torus or donut.

The radiation of many antennas shows a pattern of maxima or "lobes" at various angles, separated by "nulls", angles where the radiation falls to zero. This is because the radio waves emitted by different parts of the antenna typically interfere, causing maxima at angles where the radio waves arrive at distant points in phase, and zero radiation at other angles where the radio waves arrive out of phase. In a directional antenna designed to project radio waves in a particular direction, the lobe in that direction is designed larger than the others and is called the "main lobe". The other lobes usually represent unwanted radiation and are called "sidelobes". The axis through the main lobe is called the "principal axis" or "boresight axis".

Field regions[edit]

The space surrounding an antenna can be divided into three concentric regions: the reactive near-field, the radiating near-field (Fresnell region) and the far-field (Fraunhofer) regions. These regions are useful to identify the field structure in each, although there are no precise boundaries.

In the far-field region, we are far enough from the antenna to neglect its size and shape. We can assume that the electromagnetic wave is purely a radiating plane wave (electric and magnetic fields are in phase and perpendicular to each other and to the direction of propagation). This simplifies the mathematical analysis of the radiated field.

Impedance[edit]

As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc.). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source,^[14] forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.

Complex impedance of an antenna is related to the electrical length of the antenna at the wavelength in use. The impedance of an antenna can be matched to the feed line and radio by adjusting the impedance of the feed line, using the feed line as an impedance transformer. More commonly, the impedance is adjusted at the load (see below) with an antenna tuner, a balun, a matching transformer, matching networks composed of inductors and capacitors, or matching sections such as the gamma match.

Efficiency[edit]

Main article: Antenna efficiency

Efficiency of a transmitting antenna is the ratio of power actually radiated (in all directions) to the power absorbed by the antenna terminals. The power supplied to the antenna terminals which is not radiated is converted into heat. This is usually through loss resistance in the antenna's conductors, but can also be due to dielectric or magnetic core losses in antennas (or antenna systems) using such components. Such loss effectively robs power from the transmitter, requiring a stronger transmitter in order to transmit a signal of a given strength.

For instance, if a transmitter delivers 100 W into an antenna having an efficiency of 80%, then the antenna will radiate 80 W as radio waves and produce 20 W of heat. In order to radiate 100 W of power, one would need to use a transmitter capable of supplying 125 W to the antenna. Note that antenna efficiency is a separate issue from impedance matching, which may also reduce the amount of power radiated using a given transmitter. If an SWR meter reads 150 W of incident power and 50 W of reflected power, that means that 100 W have actually been absorbed by the antenna (ignoring transmission line losses). How much of that power has actually been radiated cannot be directly determined through electrical measurements at (or before) the antenna terminals, but would require (for instance) careful measurement of field strength. Fortunately the loss resistance of antenna conductors such as aluminum rods can be calculated and the efficiency of an antenna using such materials predicted.

However loss resistance will generally affect the feedpoint impedance, adding to its resistive (real) component. That resistance will consist of the sum of the radiation resistance R_rand the loss resistance R_loss. If an rms current I is delivered to the terminals of an antenna, then a power of I²R_r will be radiated and a power of I²R_loss will be lost as heat. Therefore the efficiency of an antenna is equal to R_r / (R_r + R_loss). Of course only the total resistance R_r + R_loss can be directly measured.

According to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very inefficient antennas may have little impact on performance. At low frequencies, for example, atmospheric or man-made noise can mask antenna inefficiency. For example, CCIR Rep. 258-3 indicates man-made noise in a residential setting at 40 MHz is about 28 dB above the thermal noise floor. Consequently, an antenna with a 20 dB loss (due to inefficiency) would have little impact on system noise performance. The loss within the antenna will affect the intended signal and the noise/interference identically, leading to no reduction in signal to noise ratio (SNR).

This is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance R_r of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle by including a small loop antenna for reception which has an extremely poor efficiency. Using such an inefficient antenna at this low frequency (530–1650 kHz) thus has little effect on the receiver's net performance, but simply requires greater amplification by the receiver's electronics. Contrast this tiny component to the massive and very tall towers used at AM broadcast stations for transmitting at the very same frequency, where every percentage point of reduced antenna efficiency entails a substantial cost.

The definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency as well. This is likewise true for a receiving antenna at very high (especially microwave) frequencies, where the point is to receive a signal which is strong compared to the receiver's noise temperature. However in the case of a directional antenna used for receiving signals with the intention of rejecting interference from different directions, one is no longer concerned with the antenna efficiency, as discussed above. In this case, rather than quoting the antenna gain, one would be more concerned with the directive gain which does not include the effect of antenna (in)efficiency. The directive gain of an antenna can be computed from the published gain divided by the antenna's efficiency.

Polarization[edit]

The polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's directionality. Thus, a simple straight wire antenna will have one polarization when mounted vertically, and a different polarization when mounted horizontally. As a transverse wave, the magnetic field of a radio wave is at right angles to that of the electric field, but by convention, talk of an antenna's "polarization" is understood to refer to the direction of the electric field.

Reflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communications or ground wave propagation, horizontally or vertically polarized transmissions generally remain in about the same polarization state at the receiving location. Matching the receiving antenna's polarization to that of the transmitter can make a very substantial difference in received signal strength.

Polarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be defined. For instance, a vertical whip antenna or Wi-Fi antenna vertically oriented will transmit and receive in the vertical polarization. Antennas with horizontal elements, such as most rooftop TV antennas, are horizontally polarized (broadcast TV usually uses horizontal polarization). Even when the antenna system has a vertical orientation, such as an array of horizontal dipole antennas, the polarization is in the horizontal direction corresponding to the current flow. The polarization of a commercial antenna is an essential specification.

Polarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases are linear polarization (the ellipse collapses into a line) as we have discussed above, and circular polarization (in which the two axes of the ellipse are equal). In linear polarization the electric field of the radio wave oscillates back and forth along one direction; this can be affected by the mounting of the antenna but usually the desired direction is either horizontal or vertical polarization. In circular polarization, the electric field (and magnetic field) of the radio wave rotates at the radio frequency circularly around the axis of propagation. Circular or elliptically polarized radio waves are designated as right-handed or left-handed using the "thumb in the direction of the propagation" rule. Note that for circular polarization, optical researchers use the opposite right hand rule from the one used by radio engineers.

It is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal linear polarizations. Transmission from a circularly polarized antenna received by a linearly polarized antenna (or vice versa) entails a 3dB reduction in signal-to-noise ratio as the received power has thereby been cut in half.

Impedance matching[edit]

Main article: Impedance matching

Maximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dynamic output impedance of the transmitter as analyzed as a source impedance but rather the design value (typically 50 ohms) required for efficient and safe operation of the transmitting circuitry. The intended impedance is normally resistive but a transmitter (and some receivers) may have additional adjustments to cancel a certain amount of reactance in order to "tweak" the match. When a transmission line is used in between the antenna and the transmitter (or receiver) one generally would like an antenna system whose impedance is resistive and near the characteristic impedance of that transmission line in order to minimize the standing wave ratio (SWR) and the increase in transmission line losses it entails, in addition to supplying a good match at the transmitter or receiver itself.

Antenna tuning generally refers to cancellation of any reactance seen at the antenna terminals, leaving only a resistive impedance which might or might not be exactly the desired impedance (that of the transmission line). Although an antenna may be designed to have a purely resistive feedpoint impedance (such as a dipole 97% of a half wavelength long) this might not be exactly true at the frequency that it is eventually used at. In some cases the physical length of the antenna can be "trimmed" to obtain a pure resistance. On the other hand, the addition of a series inductance or parallel capacitance can be used to cancel a residual capacitative or inductive reactance, respectively.

In some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a "whip antenna" can be made significantly shorter than 1/4 wavelength long, for practical reasons, and then resonated using a so-called loading coil. This physically large inductor at the base of the antenna has an inductive reactance which is the opposite of the capacitative reactance that such a vertical antenna has at the desired operating frequency. The result is a pure resistance seen at feedpoint of the loading coil; unfortunately that resistance is somewhat lower than would be desired to match commercial coax.^{[citation needed]}

So an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A general matching network with at least two adjustments can be made to correct both components of impedance. Matching networks using discrete inductors and capacitors will have losses associated with those components, and will have power restrictions when used for transmitting. Avoiding these difficulties, commercial antennas are generally designed with fixed matching elements or feeding strategies to get an approximate match to standard coax, such as 50 or 75 Ohms. Antennas based on the dipole (rather than vertical antennas) should include a balun in between the transmission line and antenna element, which may be integrated into any such matching network.

Another extreme case of impedance matching occurs when using a small loop antenna (usually, but not always, for receiving) at a relatively low frequency where it appears almost as a pure inductor. Resonating such an inductor with a capacitor at the frequency of operation not only cancels the reactance but greatly magnifies the very small radiation resistanceof such a loop.^{[citation needed]} This is implemented in most AM broadcast receivers, with a small ferrite loop antenna resonated by a capacitor which is varied along with the receiver tuning in order to maintain resonance over the AM broadcast band

Basic antenna models[edit]

There are many variations of antennas. Below are a few basic models. More can be found in Category:Radio frequency antenna types.

A "Turnstile" type transmitting antenna (two dipole antennas aligned at right angles) for a VHF low band television broadcasting station.

The isotropic radiator is a purely theoretical antenna that radiates equally in all directions. It is considered to be a point in space with no dimensions and no mass. This antenna cannot physically exist, but is useful as a theoretical model for comparison with all other antennas. Most antennas' gains are measured with reference to an isotropic radiator, and are rated in dBi (decibels with respect to an isotropic radiator).
The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically, with one end of each wire connected to the radio and the other end hanging free in space. Since this is the simplest practical antenna, it is also used as a reference model for other antennas; gain with respect to a dipole is labeled as dBd. Generally, the dipole is considered to be omnidirectional in the plane perpendicular to the axis of the antenna, but it has deep nulls in the directions of the axis. Variations of the dipole include the folded dipole, the half wave antenna, the ground plane antenna, the whip, and the J-pole.
The Yagi-Uda antenna is a directional variation of the dipole with parasitic elements added which are functionality similar to adding a reflector and lenses (directors) to focus a filament light bulb.
The random wire antenna is simply a very long (at least one quarter wavelength^{[citation needed]}) wire with one end connected to the radio and the other in free space, arranged in any way most convenient for the space available. Folding will reduce effectiveness and make theoretical analysis extremely difficult. (The added length helps more than the folding typically hurts.) Typically, a random wire antenna will also require an antenna tuner, as it might have a random impedance that varies non-linearly with frequency.
The horn antenna is used where high gain is needed, the wavelength is short (microwave) and space is not an issue. Horns can be narrow band or wide band, depending on their shape. A horn can be built for any frequency, but horns for lower frequencies are typically impractical. Horns are also frequently used as reference antennas.
The parabolic antenna consists of an active element at the focus of a parabolic reflector to reflect the waves into a plane wave. Like the horn it is used for high gain, microwave applications, such as satellite dishes.
The patch antenna consists mainly of a square conductor mounted over a groundplane. Another example of a planar antenna is the tapered slot antenna (TSA), as the Vivaldi-antenna.

Examples of antenna models[edit]

Dipole antenna ("Rabbit ears") for television reception
Folded dipole antenna
A Yagi-Uda beam antenna
Rooftop TV antenna. It is actually three Yagi antennas. The longest elements are for the low band, while the medium and short elements are for the high and UHF band.
A random wire antenna
Pyramidal microwave horn antenna
Large parabolic antennafor communicating with spacecraft
A patch antenna and a cutaway view

Practical antennas[edit]

This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2014)

"Rabbit ears" set-top antenna

Although any circuit can radiate if driven with a signal of high enough frequency, most practical antennas are specially designed to radiate efficiently at a particular frequency. An example of an inefficient antenna is the simple Hertzian dipole antenna, which radiates over a wide range of frequencies and is useful^{[citation needed]} for its small size. A more efficient variation of this is the half-wave dipole, which radiates with high efficiency when the signal wavelength is twice the electrical length of the antenna. One of the goals of antenna design is to minimize thereactance of the device so that it appears as a resistive load. An "antenna inherent reactance" includes not only the distributed reactance of the active antenna but also the natural reactance due to its location and surroundings (as for example, the capacity relation inherent in the position of the active antenna relative to ground). Reactance can be eliminated by operating the antenna at its resonant frequency, when its capacitive and inductive reactances are equal and opposite, resulting in a net zero reactive current. If this is not possible, compensating inductors or capacitors can instead be added to the antenna to cancel its reactance as far as the source is concerned. Once the reactance has been eliminated, what remains is a pure resistance, which is the sum of two parts: the ohmic resistance of the conductors, and the radiation resistance. Power absorbed by the ohmic resistance becomes waste heat, and that absorbed by the radiation resistance becomes radiated electromagnetic energy. The greater the ratio of radiation resistance to ohmic resistance, the more efficient the antenna.

Effect of ground[edit]

Antennas are typically used in an environment where other objects are present that may have an effect on their performance. Height above ground has a very significant effect on the radiation pattern of some antenna types.

At frequencies used in antennas, the ground behaves mainly as a dielectric. The conductivity of ground at these frequencies is negligible. When an electromagnetic wave arrives at the surface of an object, two waves are created: one enters the dielectric and the other is reflected. If the object is a conductor, the transmitted wave is negligible and the reflected wave has almost the same amplitude as the incident one. When the object is a dielectric, the fraction reflected depends (among other things) on the angle of incidence. When the angle of incidence is small (that is, the wave arrives almost perpendicularly) most of the energy traverses the surface and very little is reflected. When the angle of incidence is near 90° (grazing incidence) almost all the wave is reflected.

Most of the electromagnetic waves emitted by an antenna to the ground below the antenna at moderate (say < 60°) angles of incidence enter the earth and are absorbed (lost). But waves emitted to the ground at grazing angles, far from the antenna, are almost totally reflected. At grazing angles, the ground behaves as a mirror. Quality of reflection depends on the nature of the surface. When the irregularities of the surface are smaller than the wavelength, reflection is good.

The wave reflected by earth can be considered as emitted by the image antenna.

This means that the receptor "sees" the real antenna and, under the ground, the image of the antenna reflected by the ground. If the ground has irregularities, the image will appear fuzzy.

If the receiver is placed at some height above the ground, waves reflected by ground will travel a little longer distance to arrive to the receiver than direct waves. The distance will be the same only if the receiver is close to ground.

In the drawing at right, the angle has been drawn far bigger than in reality. The distance between the antenna and its image is .

The situation is a bit more complex because the reflection of electromagnetic waves depends on the polarization of the incident wave. As the refractive index of the ground (average value ) is bigger than the refractive index of the air (), the direction of the component of the electric field parallel to the ground inverses at the reflection. This is equivalent to a phase shift of radians or 180°. The vertical component of the electric field reflects without changing direction. This sign inversion of the parallel component and the non-inversion of the perpendicular component would also happen if the ground were a good electrical conductor.

The vertical component of the current reflects without changing sign. The horizontal component reverses sign at reflection.

This means that a receiving antenna "sees" the image antenna with the current in the same direction if the antenna is vertical or with the current inverted if the antenna is horizontal.

For a vertical polarized emission antenna the far electric field of the electromagnetic wave produced by the direct ray plus the reflected ray is:

The sign inversion for the parallel field case just changes a cosine to a sine:

In these two equations:

is the electrical field radiated by the antenna if there were no ground.
is the wave number.
is the wave length.
is the distance between antenna and its image (twice the height of the center of the antenna).

Radiation patterns of antennas and their images reflected by the ground. At left the polarization is vertical and there is always a maximum for . If the polarization is horizontal as at right, there is always a zero for .

For emitting and receiving antennas situated near the ground (in a building or on a mast) far from each other, distances traveled by direct and reflected rays are nearly the same. There is no induced phase shift. If the emission is polarized vertically, the two fields (direct and reflected) add and there is maximum of received signal. If the emission is polarized horizontally, the two signals subtract and the received signal is minimum. This is depicted in the image at right. In the case of vertical polarization, there is always a maximum at earth level (left pattern). For horizontal polarization, there is always a minimum at earth level. Note that in these drawings the ground is considered as a perfect mirror, even for low angles of incidence. In these drawings, the distance between the antenna and its image is just a few wavelengths. For greater distances, the number of lobes increases.

Note that the situation is different—and more complex—if reflections in the ionosphere occur. This happens over very long distances (thousands of kilometers). There is not a direct ray but several reflected rays that add with different phase shifts.

This is the reason why almost all public address radio emissions have vertical polarization. As public users are near ground, horizontal polarized emissions would be poorly received. Observe household and automobile radio receivers. They all have vertical antennas or horizontal ferrite antennas for vertical polarized emissions. In cases where the receiving antenna must work in any position, as in mobile phones, the emitter and receivers in base stations use circular polarized electromagnetic waves.

Classical (analog) television emissions are an exception. They are almost always horizontally polarized, because the presence of buildings makes it unlikely that a good emitter antenna image will appear.^{[citation needed]} However, these same buildings reflect the electromagnetic waves and can create ghost images. Using horizontal polarization, reflections are attenuated because of the low reflection of electromagnetic waves whose magnetic field is parallel to the dielectric surface near the Brewster's angle. Vertically polarized analog television has been used in some rural areas. In digital terrestrial television reflections are less obtrusive, due to the inherent robustness of digital signalling and built-in error correction.

Mutual impedance and interaction between antennas[edit]

Current circulating in one antenna generally induces a voltage across the feedpoint of nearby antennas or antenna elements; note that this now is a near field phenomenon which is not properly accounted for using the Friis transmission equation for instance. It can be described using the concept of mutual impedance between the two antennas just as the mutual impedance describes the voltage induced in one inductor by a current through a nearby coil coupled to it through a mutual inductance M. The mutual impedance between two antennas is defined^[15] as:

where is the current flowing in antenna 1 and is the voltage induced at the open-circuited feedpoint of antenna 2 due only to . This parameter also permits, for instance, the calculation of the current in antenna 2 when its feedpoint is shorted or otherwise terminated, as we shall now show.

Using the above definition, the currents and voltages present at the feedpoints of a set of coupled antennas satisfy:

where:

is the voltage at the terminals of antenna
is the current flowing between the terminals of antenna
is the driving point impedance of antenna
is the mutual impedance between antennas and .

Mutual impedance between parallel dipoles not staggered. Curves Re and Im are the resistive and reactive parts of the impedance.

As is the case for mutual inductances,

This is a consequence of Lorentz reciprocity. For an antenna element not connected to anything (open circuited) one can write . But for an element which is short circuited, a current is generated across that short but no voltage is allowed, so the corresponding . This is the case, for instance, with the so-called parasitic elements of a Yagi-Uda antenna where the solid rod can be viewed as a dipole antenna shorted across its feedpoint. Parasitic elements are unpowered elements that absorb and reradiate RF energy according to the induced current calculated using such a system of equations.

With a particular geometry, it is possible for the mutual impedance between nearby antennas to be zero. This is the case, for instance, between the crossed dipoles used in theturnstile antenna.

The History Of Student

2014-10-10T19:58:00.000-07:00

Student

Admission of a student in "Germanic Nation", University of Bologna, 15th century

Pupils in rural Sudan, 2002

A student (Also Pupil) is a learner, or someone who attends an educational institution. In some nations, the English term (or its cognate in another language) is reserved for those who attend university, while a schoolchild under the age of eighteen is called a pupil in English (or an equivalent in other languages), although in the United States and in Australia a person enrolled in grades K–12 is often called a student. In its widest use, student is used for anyone who is learning, including mid-career adults who are taking vocational education or returning to university.

International variations[edit]

Over one thousand pupils in uniform during an assembly at asecondary school in Singapore

Asia[edit]

Brunei[edit]

Education is free in Brunei Darussalam not limited to government educational institutions but private educational institutions too. There are mainly two types of educational institutions namely government or public as well as private institutions. Several stages have to be undergone by the prospective students leading to higher qualifications such as Bachelor's Degree.

Primary School (Year 1 to 6)
Secondary School (Year 7 to 11)
High School [or also known as the Sixth Form Centers] (Year 12 to 13)
Colleges (Pre-University to Diploma)
University Level (Undergraduate, Postgraduate and Professional)

It takes six and five years to complete the primary and secondary levels respectively. Upon completing these two crucial stages, students have freedom to progress the sixth-form centers, colleges or probably straight to employment. Ahead of times, these students will be leaded to undertaking the university level programs in both, government and private university colleges.

Pakistan[edit]

In Pakistan 12-year school is categorized in three stages: Primary school, Secondary school and Higher Secondary school. It takes 5 years for a student to graduate from Primary school, 3 years for Secondary school and 2 years for Higher Secondary school and 2 years for College/per-university college. On average Bachelor's degree spans over three years with exception to engineering degree that takes 4 years and 2 years Master's degree.

Philippines[edit]

The Philippines is currently in the midst of a transition to a K-12 (also called K+12) basic education system. Education ideally begins with one year of kinder. Once the transition is complete, elementary or grade school comprises grades 1 to 6. Although the term student may refer to learners of any age or level, the term pupil is used by the Department of Education to refer to learners in the elementary level, particularly in public schools. Secondary level or high school comprises two major divisions: grades 7 to 10 will be collectively referred to as 'junior high school', whereas grades 11 to 12 will be collectively referred to as 'senior high school'. The Department of Education refers to learners in grade 7 and above as students.

After basic education, students can opt to take a bachelor's (undergraduate) degree at a higher education institution (i.e. a college or university), which normally lasts for four years though the length of some courses may be longer or shorter depending on the institution.

India[edit]

In India also, 12-year school is categorized in three stages: Primary school, Secondary school and Higher Secondary school. In some states like Maharashtra and Andhra Pradesh, 2 year Higher Secondary is Junior College and the Institute is different from regular school. For College its average 3 years for Bachelor's degree (exception B. Tech. and B.E. i.e. 4 years) and 2 years Master's degree.

Iran[edit]

An Iranian Student going to her classmate house for study together at evening, in Nishapur

In Iran 12-year school is categorised in three stages: Elementary school, Junior high school and High school. It takes 5 years for a student to graduate from elementary school, 3 years for junior high school and 3 years for high school and 1 year for pre-university college( independed on your field) . After graduating from high school(or pre-university if needed), students acquire a diploma. Having a diploma, a student can participate in the Iranian University Entrance Exam or Konkoor. The university entrance exam is conducted every year by National Organization of Education Assessment, an organization under the supervision of the Ministry of Science, Research and Technology.^[1] Members of the Baha'i religion, a much-persecuted minority are officially forbidden to attend university, in order to prevent members of the faith becoming doctors, lawyers or other professionals.

Australia[edit]

Students of Stony Creek State School, Queensland, 1939

In Australia, after preschool, which is not compulsory, children begin primary school, usually after their fifth birthday. In New South Wales the first year is called 'kindergarten', in Victoria 'prep', and in South Australia 'reception'; students then continue on to 'grade one' through to 'grade six', except in Western Australia, South Australia and Queensland, where primary school currently continues to 'grade seven'. However, by 2014 all states will conclude primary schooling at 'year six'. Students begin secondary school (also known as high school) in 'year seven' (or 'year eight' in WA and Qld)and continue to 'year twelve'. Year seven/eight is referred to as the junior school, nine/ten is referred to as 'middle school' and year ten/eleven through to twelve as 'senior school'. After year twelve, students may pursue tertiary education at university or TAFE (technical and further education). The general term for people in primary, secondary and tertiary education is 'students'.

New Zealand[edit]

In New Zealand, after kindergarten or pre-school, which is attended from ages three to five, children begin primary school, 'Year One', at five years of age. Years One to Six are Primary School, where children commonly attend local schools in the area for that specific year group. Then Year Seven and Year Eight are Intermediate, and from Year Nine until Year Thirteen, a student would attend a secondary school or a college. Primary School children are known as Pupils and Intermediate/Secondary School children are known as Students.

Europe[edit]

Finland[edit]

Students in a lecture on linear algebra at the Helsinki University of Technology

In Finland a student is called "opiskelija" (plural being 'opiskelijat'), though children in compulsory education are called "oppilas" (plural being 'oppilaat'). first level of education is "esikoulu" (literally 'preschool'), which is optional. Children attend esikoulu the year they turn six, and next year they start attending "peruskoulu" (literally "basic school", corresponds to American elementary school, middle school and junior high), which is compulsory. Peruskoulu is divided to "alakoulu" (years 1 through 6) and "yläkoulu" (years 7 through 9). After compulsory education most children attend second level education (toisen asteen koulutus), either lukio (corresponds to high school) or ammattikoulu (Vocational School), at which point they are called students (opiskelija). Some attend "kymppiluokka", which is a retake on some yläkoulu's education.

To attend ammattikorkeakoulu (University of applied sciences) or a university a student must have a second level education. The recommended graduation time is five years. First year students are called "fuksi" and students that have studied more than five years are called "N:nnen vuoden opiskelija" (Nth year student).

France[edit]

In some French schools, a bleu or "bizuth" is a first-year student. Second-year students are sometimes called "carrés" (squares). Some other terms may apply in specific schools, some depending on the classe préparatoire aux grandes écoles attended. The generic term "Étudiant" (lit. Student) applies specifically to someone attending a University or a school of a similar level, that is to sat pupils in a cursus reserved to people already owning a Baccalauréat.

Germany[edit]

In Germany, the German cognate term "student" is reserved for those attending a university. University students in their first year are colloquially called Ersties ("firsties"). Different terms for school students exist, depending on which kind of school is attended by the student. The general term for a person going to school is Schüler or Schülerin. Students attending a university preparatory school are called Gymnasiasten, while those attending other schools are called Hauptschüler or Realschüler. Students who graduate with theAbitur are called Abiturienten. The abbreviation stud. + the abbreviation of the faculty p. e. phil. for philosophiae is a post-nominal for all students of a baccalaureus course. The abbreviation cand. for candidatus + the abbreviation of the faculty is given as a post-nominal to those studying for a mastership. First name surname, stud. phil. or First name surname, cand. jur.

Ireland[edit]

In Ireland, pupils officially start with primary school which consists of eight years: junior infants, senior infants, first class to sixth class (ages 5–11). After primary school, pupils proceed to the secondary school level. Here they first enter the junior cycle, which consists of first year to third year (ages 12–15). At the end of third year, all students must sit a compulsory state examination called the Junior Certificate. After third year, pupils have the option of taking a "transition year" or fourth year (usually at age 15-16). In transition year pupils take a break from regular studies to pursue other activities that help to promote their personal, social, vocational and educational development, and to prepares them for their role as autonomous, participative and responsible members of society. It also provides a bridge to enable pupils to make the transition from the more dependent type of learning associated with the Junior Cert. to the more independent learning environment associated with the senior cycle.

After the junior cycle pupils advance to the senior cycle, which consists of fifth year and sixth year (usually ages between 16 to 18). At the end of the sixth year a final state examination is required to be sat by all pupils, known as the Leaving Certificate. The Leaving Cert. is the basis for all Irish pupils who wish to do so to advance to higher education via a points system. A maximum of 600 points can be achieved. All higher education courses have a minimum of points needed for admission.

At Trinity College, Dublin under-graduate students are formally called "junior freshmen", "senior freshmen", "junior sophister" or "senior sophister", according to the year they have reached in the typical four year degree course. Sophister is another term for a sophomore, though the term is rarely used in other institutions and is largely limited to Trinity College Dublin.

At university the term "fresher" is used to describe new students who are just beginning their first year. The term, "first year" is the more commonly used and connotation-free term for students in their first year. The week at the start of a new year is called "Freshers' Week" or "Welcome Week", with a programme of special events to welcome new students. An undergraduate in the last year of study before graduation is generally known as a "finalist."

Italy[edit]

In Italian, a matricola is a first-year student. Some other terms may apply in specific schools, some depending on the liceo classico or liceo scientifico attended.

Sweden[edit]

In Sweden, only those studying at university level are called students (student, plural studenter). To graduate from upper secondary school (gymnasium) is called ta studenten(literally "to take the student"), but after the graduation festivities, the graduate is no longer a student unless he or she enrolls at university-level education. At lower levels, the wordelev (plural elever) is used. As a general term for all stages of education, the word studerande (plural also studerande) is used, meaning 'studying [person]'.

United Kingdom[edit]

The new graduates of the Europa-Institut in Germany gather to throw their mortar boards in the air as part of a graduation ceremony

Traditionally, the term "student" is reserved for people studying at university level in the United Kingdom. Children studying at school are called "pupils" or "schoolchildren" (or "schoolboys" or "schoolgirls"). However, the American English use of the word "student" to include pupils of all ages, even at elementary level, is now spreading to other countries, and is occasionally found in the UK (particularly in the state sector), as well as Australia and Singapore. In South Africa, the term "learner" is also used.

In England and Wales, teenagers who attend a college or secondary school for further education are typically called "sixth formers". If pupils follow the average pattern of school attendance, pupils will be in "year 12" between the ages of 16 and 17, and "year 13" between 17 and 18, however many schools still refer to them as the "lower sixth" and "upper sixth" or "AS" and "A2". The successful completion of VI Form and the acquisition of A Level qualifications is the traditional path to university education.

In Scotland, pupils sit Highers at the end of fifth year (when aged 16–17) after which it is possible for them to gain entry to university. Many pupils, however, choose to remain at school for a sixth year to grow in maturity and to gain extra qualifications (e.g. Advanced Highers).

At universities in the UK, the term "fresher" is used informally to describe new students who are just beginning their first year. Although it is not unusual to call someone a fresher after their first few weeks at university, they are typically referred to as "first years" or "first year students".

The ancient Scottish University of St Andrews uses the terms "bejant" for a first year (from the French "bec-jaune" – "yellow beak", "fledgling"). Second years are called "semi-bejants", third years are known as "tertians", and fourth years, or others in their final year of study, are called "magistrands".

In England and Wales, primary school begins with an optional "nursery" year followed by reception and then move on to "year one, year two" and so on until "year six". In state schools, children join secondary school when they are 11–12 years old in what used to be called "first form" and is now known as "year 7". They go up to year 11 (formerly "fifth form") and then join the sixth form, either at the same school or at a separate sixth form college. A student entering a private, fee-paying school (usually at age 13) would join the "third form" — equivalent to year 9. Many schools have an alternate name for first years, some with a derogatory basis, but in others acting merely as a description — for example "shells" (non-derogatory) or "grubs" (derogatory).

In Northern Ireland and Scotland, it is very similar but with some differences. Pupils start off in nursery or reception aged 3 to 4, and then start primary school in "P1" (P standing for primary) or year 1. They then continue primary school until "P7" or year 7. After that they start secondary school at 11 years old, this is called "1st year" or year 8 in Northern Ireland, or "S1" in Scotland. They continue secondary school until the age of 16 at "5th year", year 12 or "S5", and then it is the choice of the individual pupil to decide to continue in school and (in Northern Ireland) do AS levels (known as "lower sixth") and then the next year to do A levels (known as "upper sixth"). In Scotland, students aged 16–18 take Highers, followed by Advanced Highers. Alternatively, pupils can leave and go into full-time employment or to start in a technical college.

Large increases in the size of student populations in the UK and the effect this has had on some university towns or on areas of cities located near universities have become a concern in the UK since 2000. A report by Universities UK, "Studentification: A Guide to Opportunities, Challenges and Practice" (2006) has explored the subject and made various recommendations.^[2] A particular problem in many locations is seen as the impact of students on the availability, quality and price of rented and owner-occupied property.

North America[edit]

Canada[edit]

For more details on this topic, see Education in Canada.

Students of the Cégep de St-Hyacinthe in Quebec working in a computer lab

Education in Canada is within the constitutional jurisdiction of the provinces, and the overall curriculum is overseen by the provincial governments. As there is no overall national coordinating authority, the way the educational stages are grouped and named differs from region to region. Education is generally divided into primary education, followed by secondary education, and post-secondary education. Primary and secondary education are generally divided into numbered grades from 1 to 12, although the first grade may be preceded bykindergarten (optional in many provinces). Ontario and Quebec offer a pre-kindergarten, called a "junior kindergarten" in Ontario, and a "garderie" in Quebec.

Education in Ontario once involved an Ontario Academic Credit (OAC) as university preparation, but that was phased out in 2007, and now all provinces except Quebec have 12 grades. The OAC was informally known as "grade 13" and the name was also used to refer to the students who took it.

Education in Quebec differs from the other provinces in that it has an école primaire (literally "primary school") consisting of grades 1-6, and an école secondaire (literally "secondary school") consisting of secondaries I-V. Secondaries I-V are equivalent to grades 7-11. A student graduating from high school (grade 11) can then either complete a three year college program or attend a two year pre-university program required before attending university. In some English High Schools, as well as in most French schools, high school students will refer to secondary 1-5 as year one through five. So if someone in Secondary three is asked "what grade/year are you in?" they will reply "three" or "sec 3". It is presumed that the person asking the question knows that they are not referring to "Grade 3" but rather "Secondary 3". This can be confusing for those outside of Quebec.

In some provinces, grades 1 through 6 are called "elementary school", grades 6 through 8 are called "middle school" or "junior high school", and grades 9 through 12 are considered high school. Other provinces, such as British Columbia, mainly divide schooling into elementary school (Kindergarten to grade 7) and secondary school (grades 8 through 12). In Alberta and Nova Scotia, elementary consists of kindergarten through grade 6. Junior high consists of Grades 7-9. High school consists of Grades 10-12. In English provinces, the high school (known as academy or secondary school) years can be referred to simply as first, second, third, and fourth year. Some areas call it by grade such as grade 10, grade 11, and grade 12.

The difference between college and university is significantly different from in the United States or even the United Kingdom. A Canadian college is more similar to an American community college. In contrast, a Canadian university is comparable to an American university. In Canada, colleges are generally geared for individuals seeking applied careers, while universities are geared for individuals seeking more academic careers.

University students are generally classified as first, second, third, or fourth-year students, and the American system of classifying them as "freshmen", "sophomores", "juniors", and "seniors" is seldom used or even understood in Canada. In some occasions, they can be called "senior ones", "twos", "threes", and "fours".

United States[edit]

In the United States, the first official year of schooling is called kindergarten, which is why the students are called kindergarteners. Kindergarten is optional in most states, but few students skip this level. Pre-kindergarten, also known as "preschool" (and sometimes shortened to "Pre-K") is becoming a standard of education as academic expectations for the youngest students continue to rise. Many public schools offer pre-kindergarten programs.

In the United States there are 12 years of mandatory schooling. The first eight are solely referred to by numbers (e.g. 1st grade, 5th grade) so students may be referred to as 1st graders, 5th graders, etc. Upon entering high school, grades 9 through 12 (high school) also have alternate names for students, namely Freshman, Sophomore, Junior and Senior. The actual divisions of which grade levels belong to which division (whether elementary, middle, junior high, or high school) is a matter decided by state or local jurisdictions.

Accordingly, college students are often called Freshman, Sophomores, Juniors, and Seniors (respectively), unless their undergraduate program calls for more than the traditional 4 years.

First year[edit]

The first year of college or high school is referred to as Freshman year. A freshman (slang alternatives that are usually derogatory in nature include "fish", "new-g", "fresher", "frosh", "newbie", "freshie", "snotter", "fresh-meat", "skippie", etc.) is a first-year student in college, university or high school. The less-common^{[citation needed]} gender-neutral synonym "first-year student" exists.

Second year[edit]

In the U.S., a sophomore, also called a "soph," is a second-year student. Outside the United States, the term Sophomore is rarely used, with second-year students simply called "second years". Folk etymology indicates that the word means "wise fool"; consequently "sophomoric" means "pretentious, bombastic, inflated in style or manner; immature, crude, superficial" (according to the Oxford English Dictionary). It is widely assumed to be formed from Greek "sophos", meaning "wise", and "moros" meaning "foolish", although the etymology suggests an origin from the now-defunct "sophumer", an obsolete variant of "sophism".^[3]

Post-second year[edit]

Students from the Massachusetts Institute of Technology

In the U.S., a Junior is a student in the penultimate (usually third) year and a Senior is a student in the last (usually fourth) year of college,university, or high school. A student who takes more than the normal number of years to graduate is sometimes referred to as a "super senior".^[4] This term is often used in college, but can be used in high school as well. The term Underclassman is used to refer collectively to Freshmen and Sophomores, and Upperclassman to refer collectively to Juniors and Seniors, sometimes even Sophomores. The term Middler is used to describe a third-year student of a school (generally college) that offers five years of study. In this situation, the fourth and fifth years would be referred to as Junior and Senior years, respectively, and the first two years would be the Freshman and Sophomore years.

Graduate Students[edit]

A Graduate student is a student who continues his/her education after graduation. Some examples of graduate programs are: law school, medical school, veterinary school. Degrees earned in Graduate programs are the Master’s degree or a Doctorate degree.

Vocational School[edit]

Students attending vocational school focus on their jobs and learning how to work in specific fields of work. A vocational program typically takes much less time to complete than a four-year degree program, lasting 12–24 months.^[5] Liberal Arts that are required in four-year Universities are less important to these students because the skills necessary for their careers take precedence in order for a timely completion of the program.

Jamaica[edit]

In Jamaica, children usually start attending school at the age of two, where they would go to what is known as basic school or kindergarten. They would then move on to the primary or preparatory school at about the age of five or six usually. After six years at this level, students would move on to the secondary school level. After five years of education at this level, some students finish (fifth form or 11th grade) and graduate at sixteen years old. Some move on to the tertiary level, while some may choose to attend 6th form (12th and 13th grade) then move on to university or college or straight into the working world.^{[citation needed]}

Mature students[edit]

Main article: Adult learner

A mature, non-traditional, or adult student in tertiary education (at a university or a college) is normally classified as an (undergraduate) student who is at least 21–23 years old at the start of their course and usually having been out of the education system for at least two years. Mature students can also include students who have been out of the education system for decades, or students with no secondary education. Mature students also make up graduate and postgraduate populations by demographic of age.

Student pranks[edit]

Main article: Student prank

University students have been associated with pranks and japes since the creation of universities in the Middle Ages.^[6]^[7]^[8]^[9]^[10] These can often involve petty crime, such as the theft of traffic cones and other public property,^[11] or hoaxes. It is also not uncommon for students from one school to steal or deface the mascot of a rival school.^[12] In fact, pranks play such a significant part in student culture that numerous books have been published that focus on the issue.^[13]^[14] Pranks may reflect current events,^[15] be a form of protest or revenge, or have no other purpose than for the enjoyment of the prank itself.

Other terms[edit]

Students who are repeating a grade level of schooling due to poor grades are sometimes referred to as having been "held back" or "kept back". In Singapore they are described as "retained". In the Philippines they are called "repeater".

The term 'pupil' (originally a Latin term for a minor as the ward of an adult guardian, etc.) is used in some Commonwealth primary and secondary schools (particularly in England and Wales) instead of "student", but once attending higher education such as sixth-form college, etc., the term "student" is standard. The term pupil is also used in the Philippines by the Department of Education to refer to learners currently in elementary school; the term student is used for by the Department of Education for learners in high school.

The United States military academies officially use only numerical terms, but there are colloquial expressions used in everyday speech. In order from first year to fourth year, students are referred to as "fourth-class", "third-class", "second-class", and "first-class" cadets or midshipmen. Unofficially, other terms are used, for example at the United States Military Academy, freshmen are called "plebes", sophomores are called "yearlings" or "yuks", juniors are called "cows", and seniors are called "firsties". Some universities also use numerical terms to identify classes; students enter as "first-years" and graduate as "fourth-years" (or, in some cases, "fifth-years", "sixth-years", etc.).

Idiomatic use[edit]

"Freshman" and "sophomore" are sometimes used figuratively, almost exclusively in the United States, to refer to a first or second effort ("the singer's sophomore album"), or to apolitician's first or second term in office ("freshman senator") or an athlete's first or second year on a professional sports team. "Junior" and "senior" are not used in this figurative way to refer to third and fourth years or efforts, because of those words' broader meanings of "younger" and "older." A junior senator is therefore not one who is in a third term of office, but merely one who has not been in the Senate as long as the other senator from their state. Confusingly, this means that it is possible to be both a "freshman Senator" and a "senior Senator" simultaneously: for example, if a Senator wins election in 2008, and then the other Senator from the same state steps down and a new Senator elected in 2010, the former Senator is both senior Senator (as in the Senate for two years more) and a freshman Senator (since still in the first term).

International Students' Day[edit]

International Students' Day commemorates the anniversary of the 1939 Nazi storming of the University of Prague after student demonstrations against the German occupation of Czechoslovakia. Germans closed all Czech universities and colleges, sent over 1200 students to Nazi concentration camps, and had nine student leaders executed (on November 17).^[16]

The History of Career

2014-10-04T18:46:00.001-07:00

Career

This article is about a person's occupational history. For the board game, see Careers (board game). For the films, see Career (film).

A career is an individual's journey through learning, work and other aspects of life. There are a number of ways to define a career and the term is used in a variety of ways.

Definitions and etymology[edit]

Career is defined by the Oxford English Dictionary as a person's "course or progress through life (or a distinct portion of life)". In this definition career is understood to relate to a range of aspects of an individual's life, learning and work. Career is also frequently understood to relate to the working aspects of an individuals life e.g. as in career woman. A third way in which the term career is used to describe an occupation or a profession that usually involves special training or formal education,^[1] and is considered to be a person’s lifework.^[2] In this case "a career" is seen as a sequence of related jobs usually pursued within a single industry or sector e.g. "a career in law" or "a career in the building trade".

The etymology of the term comes from the French word carriere (16 c.) ("road, racecourse") which, in turn, comes from the Latin word "(via) cararia" (track for wheeled vehicles) which originated from the Latin word carrus" which means "wagon".^{[citation needed]}

Historic changes in careers[edit]

For a pre-modernist notion of "career", compare cursus honorum.

By the late 20th century, a wide range of choices (especially in the range of potential professions) and more widespread education had allowed it to become possible to plan (or design) a career: in this respect the careers of the career counselor and of the career advisor have grown up. It is also not uncommon for adults in the late 20th/early 21st centuries to have dual or multiple careers, either sequentially or concurrently. Thus, professional identities have become hyphenated or hybridized to reflect this shift in work ethic. EconomistRichard Florida notes this trend generally and more specifically among the "creative class".

Career management[edit]

Career management describes the active and purposeful management of a career by an individual. Ideas of what comprise "career management skills" are describe by the Blueprint model (in the United States, Canada, Australia, Scotland, and England^[3])^[4] and the Seven C's of Digital Career Literacy (specifically relating to the Internet skills).^[5]

Key skills include the ability to reflect on one's current career, research the labour market, determine whether education is necessary, find openings, and make career changes.

Career choice[edit]

Further information: List of largest employers and List of professions

According to Behling and others, an individual's decision to join a firm may depend on any of the three factors viz. objective factor, subjective factor and critical contact.^[6]

Objective factor theory assumes that the applicants are rational. The choice, therefore, is exercised after an objective assessment of the tangible benefits of the job. Factors may include the salary, other benefits, location, opportunities for career advancement, etc.
Subjective factor theory suggests that decision making is dominated by social and psychological factors. The status of the job, reputation of the organization and other similar factors plays an important role.
Critical contact theory advances the idea that a candidate's observations while interacting with the organization plays a vital role in decision making. For example, how the recruiter keeps in touch with the candidate, the promptness of response and similar factors are important. This theory is more valid with experienced professionals.

These theories assume that candidates have a free choice of employers and careers. In reality the scarcity of jobs and strong competition for desirable jobs severely skews the decision making process. In many markets employees work particular careers simply because they were forced to accept whatever work was available to them. Additionally, Ott-Holland and colleagues found that culture can have a major influence on career choice, depending on the type of culture.^[7]

When choosing a career that's best for you, according to US News, there are multiple things to consider. Some of those include: natural talents, work style, social interaction, work-life balance, whether or not you are looking to give back, whether you are comfortable in the public eye, dealing with stress or not, and finally, how much money you want to make. If choosing a career feels like too much pressure, here's another option: pick a path that feels right today by making the best decision you can, and know that you can change your mind in the future. In today's workplace, choosing a career doesn't necessarily mean you have to stick with that line of work for your entire life. Make a smart decision, and plan to re-evaulate down the line based on your long-term objectives. ^[8]

Career (occupation) changing[edit]

Changing occupation is an important aspect of career and career management. Over a lifetime, both the individual and the labour market will change; it is to be expected that many people will change occupations during their lives. Data collected by the U.S. Bureau of Labor Statistics through the National Longitudinal Survey of Youth in 1979 showed that individuals between the ages of 18 and 38 will hold more than 10 jobs.^[9]

A survey conducted by Right Management^[10] suggests the following reasons for career changing.

The downsizing or the restructuring of an organization (54%).
New challenges or opportunities that arise (30%).
Poor or ineffective leadership (25%).
Having a poor relationship with a manager(s) (22%).
For the improvement of work/life balance (21%).
Contributions are not being recognized (21%).
For better compensation and benefits (18%),
For better alignment with personal and organizational values (17%).
Personal strengths and capabilities are not a good fit with an organization (16%).
The financial instability of an organization (13%).
An organization relocated (12%).

According to an article on Time.com, one out of three people currently employed (as of 2008) spends about an hour per day searching for another position.^[10]

Career support[edit]

There are a range of different educational, counselling and human resource management interventions that can support individuals to develop and manage their careers. Career support is commonly offered while people are in education, when they are transitioning to the labour market, when they are changing career, during periods of unemployment, and during transition to retirement. Support may be offered by career professionals, other professionals or by non-professionals such as family and friends. Professional career support is sometimes known as "career guidance" as in the OECD definition of career guidance:

The activities may take place on an individual or group basis, and may be face-to-face or at a distance (including helplines and web-based services). They include career information provision (in print, ICT-based and other forms), assessment and self-assessment tools, counselling interviews, career education programmes (to help individuals develop their self-awareness, opportunity awareness, and career management skills), taster programmes (to sample options before choosing them), work search programmes, and transition services."^[11]

However this use of the term "career guidance" can be confusing as the term is also commonly used to describe the activities of career counselors.

Provision of career support[edit]

Career support is offered by a range of different mechanisms. Much career support is informal and provided through personal networks or existing relationships such as management. There is a market for private career support however the bulk of career support that exists as a professionalised activity is provided by the public sector.^{[citation needed]}

Types of career support[edit]

Key types of career support include:

Career information describes information that supports career and learning choices. An important sub-set of career information is labour market information (LMI), such as salaries of various professions, employment rate in various professions, available training programs, and current job openings and .

Career assessments are tests that come in a variety of forms and rely on both quantitative and qualitative methodologies. Career assessments can help individuals identify and better articulate their unique interests, personality, values, and skills to determine how well they may match with a certain career. Some skills that career assessments could help determine are job-specific skills, transferable skills, and self-management skills.^[12] Career assessments can also provide a window of potential opportunities by helping individuals discover the tasks, experience, education and training that is needed for a career they would want to pursue.^[13] Career counselors, executive coaches, educational institutions, career development centers, and outplacement companies often administer career assessments to help individuals focus their search on careers that closely match their unique personal profile.

Career counseling assesses people's interests, personality, values and skills, and helps them to explore career options and research graduate and professional schools. Career counseling provides one-on-one or group professional assistance in exploration and decision making tasks related to choosing a major/occupation, transitioning into the world of work or further professional training.

Career education describes a process by which individuals come to learn about themselves, their careers and the world of work. There is a strong tradition of career education in schools,^[14] however career education can also occur in a wider range of other contexts including further and higher education and the workplace. A commonly used framework for careers education is DOTS which stands for decision learning (D), opportunity awareness (O), transition learning (T), and self-awareness (S).^[15] Oftentimes, higher education is thought of as being too narrow or too researched based and lacking of a deeper understanding of the material to develop the skills necessary for a certain career.^[16]

Some research shows adding one year of schooling beyond high school creates an increase of wages 17.8% per worker. However, additional years of schooling, beyond 9 or 10 years, have little effect on worker's wages. In summary, better educated, bigger benefits. In 2010, 90% of the U.S. Workforce had a high school diploma, 64% had some college, and 34% had at least a bachelor's degree.^[17]

The common problem that people may encounter when trying to achieve an education for a career is the cost. The career that comes with the education must pay well enough to be able to pay off the schooling. The benefits of schooling can differ greatly depending on the degree (or certification) obtained, the programs the school may offer, and the ranking of the school. Sometimes, colleges provide students more with just education to prepare for careers. It is not uncommon for colleges to provide pathways and support straight into the workforce the students may desire.^[18]

Much career support is delivered face-to-face, but an increasing amount of career support is delivered online.

The History of Online Advertising

2014-09-25T01:42:00.003-07:00

Online advertising

Internet marketing
Part of a series on
Search engine optimization Social media marketing Email marketing Referral marketing Content marketing Native advertising
Search engine marketing
Pay per click Cost per impression Search analytics Web analytics
Display advertising
Contextual advertising Behavioral targeting
Affiliate marketing
Cost per action Revenue sharing
Mobile advertising
v t e

E-commerce
Part of a series on
Online goods and services
E-books Software Streaming media
Retail services
Banking DVD-by-mail Flower delivery Food ordering Pharmacy Travel
Marketplace services
Advertising Auctions Comparison shopping Social commerce Trading communities Wallet
Mobile commerce
Payment Ticketing
Customer service
Call centre Help desk Live support software
E-procurement
Purchase-to-pay
v t e

Marketing
Key concepts
Product marketing Pricing Distribution Service Retail Brand management Brand licensing Account-based marketing Ethics Effectiveness Research Segmentation Strategy Activation Management Dominance Marketing operations Social marketing Identity Digital marketing
Promotional contents
Advertising Branding Underwriting spot Direct marketing Personal sales Product placement Publicity Sales promotion Sex in advertising Loyalty marketing Mobile marketing Premiums Prizes Corporate anniversary On-hold messaging
Promotional media
Printing Publication Broadcasting Out-of-home advertising Internet Point of sale Merchandise In-game advertising Product demonstration Word-of-mouth Brand ambassador Drip marketing Visual merchandising
v t e

Online advertising, also called online marketing or Internet advertising, is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. Like other advertising media, online advertising frequently involves both a publisher, who integrates advertisements into its online content, and an advertiser, who provides the advertisements to be displayed on the publisher's content. Other potential participants include advertising agencies who help generate and place the ad copy, an ad server who technologically delivers the ad and tracks statistics, and advertising affiliates who do independent promotional work for the advertiser.

Online advertising is a large business and is growing rapidly. In 2011, Internet advertising revenues in the United States surpassed those of cable television and nearly exceeded those of broadcast television.^[1]^:19 In 2012, Internet advertising revenues in the United States totaled $36.57 billion, a 15.2% increase over the $31.74 billion in revenues in 2011.^[1]^:4–5 U.S. internet ad revenue hit a historic high of $20.1 billion for the first half of 2013, up 18% over the same period in 2012. ^[2] Online advertising is widely used across virtually all industry sectors.^[1]^:16

Many common online advertising practices are controversial and increasingly subject to regulation. Online ad revenues may not adequately replace other publishers' revenue streams. Declining ad revenue has led some publishers to hide their content behindpaywalls.^[3]

History[edit]

In early days of the Internet, online advertising wasn't allowed. For example, two of the predecessor networks to the Internet, ARPANET and NSFNet, had "acceptable use policies" that banned network "use for commercial activities by for-profit institutions".^[4]^[5] The NSFNet began phasing out its commercial use ban in 1991.^[6]^[7]^[8]^[9]^[10]

Email. The first widely publicized example of online advertising was conducted via electronic mail. On 3 May 1978, a marketer from DEC (Digital Equipment Corporation), Gary Thuerk, sent an email to most of the ARPANET's American west coast users, advertising an open house for a new model of a DEC computer.^[5]^[11] Despite the prevailing acceptable use policies, electronic mail marketing rapidly expanded^[12] and eventually became known as “spam.”

The first known large-scale non-commercial spam message was sent on 18 January 1994 by an Andrews University system administrator, by cross-posting a religious message to allUSENET newsgroups.^[13] Four months later, Laurence Canter and Martha Siegel, partners in a law firm, broadly promoted their legal services in a USENET posting titled "Green Card Lottery – Final One?”^[14] Canter and Siegel's Green Card USENET spam raised the profile of online advertising, stimulating widespread interest in advertising via both Usenet and traditional email.^[13] More recently, spam has evolved into a more industrial operation, where spammers use armies of virus-infected computers (botnets) to send spam remotely.^[11]

Display Ads. Online banner advertising began in the early 1990s as page owners sought additional revenue streams to support their content. Commercial online service Prodigydisplayed banners at the bottom of the screen to promote Sears products.^[15] The first clickable web ad was sold by Global Network Navigator in 1993 to a Silicon Valley law firm.^[16]In 1994, web banner advertising became mainstream when HotWired, the online component of Wired Magazine, sold banner ads to AT&T and other companies. The first AT&T ad on HotWired had a 44% click-through rate, and instead of directing clickers to AT&T's website, the ad linked to an online tour of seven of the world's most acclaimed art museums.^[17]^[18]

Search Ads. GoTo.com (renamed Overture in 2001, and acquired by Yahoo! in 2003) created the first search advertising keyword auction in 1998.^[19]^:119 Google launched its "AdWords" search advertising program in 2000^[20] and introduced quality-based ranking allocation in 2002,^[21] which sorts search advertisements by a combination of bid price and searchers' likeliness to click on the ads.^[19]^:123

Recent Trends. More recently, companies have sought to merge their advertising messages into editorial content or valuable services. Examples include Red Bull's Red Bull Media House streaming Felix Baumgartner's jump from space online, Coca-Cola's online magazines, and Nike's free applications for performance tracking.^[18] Advertisers are also embracing social media^[22]^[23] and mobile advertising; mobile ad spending has grown 90% each year from 2010 to 2013.^[1]^:13

Delivery Methods[edit]

Display advertising[edit]

Display advertising conveys its advertising message visually using text, logos, animations, videos, photographs, or other graphics. Display advertisers frequently target users with particular traits to increase the ads' effect. Online advertisers (typically through their ad servers) often use cookies, which are unique identifiers of specific computers, to decide which ads to serve to a particular consumer. Cookies can track whether a user left a page without buying anything, so the advertiser can later retarget the user with ads from the site the user visited.^[24]

As advertisers collect data across multiple external websites about a user's online activity, they can create a detailed picture of the user's interests to deliver even more targeted advertising. This aggregation of data is called behavioral targeting.^[25] Advertisers can also target their audience by using contextual and semantic advertising to deliver display ads related to the content of the web page where the ads appear.^[19]^:118 Retargeting, behavioral targeting, and contextual advertising all are designed to increase an advertiser's return on investment, or ROI, over untargeted ads.^[26]

Advertisers may also deliver ads based on a user's suspected geography through geotargeting. A user's IP address communicates some geographic information (at minimum, the user's country or general region). The geographic information from an IP can be supplemented and refined with other proxies or information to narrow the range of possible locations.^[27] For example, with mobile devices, advertisers can sometimes use a phone's GPS receiver or the location of nearby mobile towers.^[28] Cookies and other persistent data on a user's machine may provide help narrowing a user's location further.^[27]

Web banner advertising[edit]

Web banners or banner ads typically are graphical ads displayed within a web page. Many banner ads are delivered by a central ad server.

Banner ads can use rich media to incorporate video, audio, animations, buttons, forms, or other interactive elements using Java applets, HTML5, Adobe Flash, and other programs.

Frame ad (traditional banner)[edit]

Frame ads were the first form of web banners.^[17] The colloquial usage of "banner ads" often refers to traditional frame ads. Website publishers incorporate frame ads by setting aside a particular space on the web page. The Interactive Advertising Bureau's Ad Unit Guidelines proposes standardized pixel dimensions for ad units.^{[citation needed]}

Pop-ups/pop-unders[edit]

A pop-up ad is displayed in a new web browser window that opens above a website visitor's initial browser window.^[29] A pop-under ad opens a new browser window under a website visitor's initial browser window.^[1]^:22

Floating ad[edit]

A floating ad, or overlay ad, is a type of rich media advertisement that appears superimposed over the requested website's content. Floating ads may disappear or become less obtrusive after a preset time period.

Expanding ad[edit]

An expanding ad is a rich media frame ad that changes dimensions upon a predefined condition, such as a preset amount of time a visitor spends on a webpage, the user's click on the ad, or the user's mouse movement over the ad.^[30] Expanding ads allow advertisers to fit more information into a restricted ad space.

Trick banners[edit]

A trick banner is a banner ad where the ad copy imitates some screen element users commonly encounter, such as an operating system message or popular application message, to induce ad clicks.^[31] Trick banners typically do not mention the advertiser in the initial ad, and thus they are a form of bait-and-switch.^[32]^[33] Trick banners commonly attract a higher-than-average click-through rate, but tricked users may resent the advertiser for deceiving them.^[34]

Interstitial ads[edit]

An interstitial ad displays before a user can access requested content, sometimes while the user is waiting for the content to load.^[35] Interstitial ads are a form of interruption marketing.^[36]^[37]

Text ads[edit]

A text ad displays text-based hyperlinks. Text-based ads may display separately from a web page's primary content, or they can be embedded by hyperlinking individual words or phrases to advertiser's websites. Text ads may also be delivered through email marketing or text message marketing. Text-based ads often render faster than graphical ads and can be harder for ad-blocking software to block.^[38]

Search Engine Marketing (SEM)[edit]

Search Engine Marketing, or SEM, is designed to increase a website's visibility in search engine results pages (SERPs). Search engines provide sponsored results and organic (non-sponsored) results based on a web searcher's query.^[19]^:117 Search engines often employ visual cues to differentiate sponsored results from organic results. Search engine marketing includes all of an advertiser's actions to make a website's listing more prominent for topical keywords.

Search Engine Optimization (SEO)[edit]

Search Engine Optimization, or SEO, attempts to improve a website's organic search rankings in SERPs by increasing the website content's relevance to search terms. Search engines regularly update their algorithms to penalize poor quality sites that try to game their rankings, making optimization a moving target for advertisers.^[39]^[40]^[41] Many vendors offer SEO services.^[1]^:22

Social media marketing[edit]

Social media marketing is commercial promotion conducted through social media websites. Many companies promote their products by posting frequent updates and providing special offers through their social media profiles.^[43]

Mobile Advertising[edit]

Mobile advertising is ad copy delivered through wireless mobile devices such as smartphones, feature phones, or tablet computers. Mobile advertising may take the form of static or rich media display ads, SMS (Short Message Service) or MMS (Multimedia Messaging Service) ads, mobile search ads, advertising within mobile websites, or ads within mobile applications or games (such as interstitial ads, “advergaming,” or application sponsorship).^[1]^:23 Industry groups such as the Mobile Marketing Association have attempted to standardize mobile ad unit specifications, similar to the IAB's efforts for general online advertising.^[37]

Mobile advertising is growing rapidly for several reasons. There are more mobile devices in the field, connectivity speeds have improved (which, among other things, allows for richer media ads to be served quickly), screen resolutions have advanced, mobile publishers are becoming more sophisticated about incorporating ads, and consumers are using mobile devices more extensively.^[1]^:14 The Interactive Advertising Bureau predicts continued growth in mobile advertising with the adoption of location-based targeting and other technological features not available or relevant on personal computers.^[1]^:14 In July 2014 Facebook reported advertising revenue for the June 2014 quarter of $2.68 billion, an increase of 67 per cent over the second quarter of 2013. Of that, mobile advertising revenue accounted for around 62 per cent, an increase of 41 per cent on the previous year.

Email Advertising[edit]

Email advertising is ad copy comprising an entire email or a portion of an email message.^[1]^:22 Email marketing may be unsolicited, in which case the sender may give the recipient an option to opt-out of future emails, or it may be sent with the recipient's prior consent (opt-in).

Chat advertising[edit]

As opposed to static messaging, chat advertising refers to real time messages dropped to users on certain sites. This is done by the usage of live chat software or tracking applications installed within certain websites with the operating personnel behind the site often dropping adverts on the traffic surfing around the sites. In reality this is a subset of the email advertising but different because of its time window.

Online classified advertising[edit]

Online classified advertising is advertising posted online in a categorical listing of specific products or services. Examples include online job boards, online real estate listings, automotive listings, online yellow pages, and online auction-based listings.^[1]^:22 Craigslist and eBay are two prominent providers of online classified listings.

Adware[edit]

Adware is software that, once installed, automatically displays advertisements on a user's computer. The ads may appear in the software itself, integrated into web pages visited by the user, or in pop-ups/pop-unders.^[44] Adware installed without the user's permission is a type of malware.^[45]

Affiliate Marketing[edit]

Affiliate marketing (sometimes called lead generation) occurs when advertisers organize third parties to generate potential customers for them. Third-party affiliates receive payment based on sales generated through their promotion.^[1]^:22

Compensation Methods[edit]

Advertisers and publishers use a wide range of payment calculation methods. In 2012, advertisers calculated 32% of online advertising transactions on a cost-per-impression basis, 66% on customer performance (e.g. cost per click or cost per acquisition), and 2% on hybrids of impression and performance methods.^[1]^:17

CPM (Cost Per Mille)[edit]

Cost per mille, often abbreviated to CPM, means that advertisers pay for every thousand displays of their message to potential customers (mille is the Latin word for thousand). In the online context, ad displays are usually called "impressions." Definitions of an "impression" vary among publishers,^[46] and some impressions may not be charged because they don't represent a new exposure to an actual customer.^[47] Advertisers can use technologies such as web bugs to verify if an impression is actually delivered.^[48]^[49]^:59

Publishers use a variety of techniques to increase page views, such as dividing content across multiple pages, repurposing someone else's content, using sensational titles, or publishing tabloid or sexual content.^[50]

CPM advertising is susceptible to "impression fraud,” and advertisers who want visitors to their sites may not find per-impression payments a good proxy for the results they desire.^[51]^:1–4

CPC (cost per click)[edit]

CPC (Cost Per Click) or PPC (Pay per click) means advertisers pay each time a user clicks on the ad. CPC advertising works well when advertisers want visitors to their sites, but it's a less accurate measurement for advertisers looking to build brand awareness.^[52] CPC's market share has grown each year since its introduction, eclipsing CPM to dominate two-thirds of all online advertising compensation methods.^[1]^:18^[51]^:1

Like impressions, not all recorded clicks are valuable to advertisers. GoldSpot Media reported that up to 50% of clicks on static mobile banner ads are accidental and resulted in redirected visitors leaving the new site immediately.^[53]

CPE (cost per engagement)[edit]

Cost per engagement aims to track not just that an ad unit loaded on the page (i.e., an impression was served), but also that the viewer actually saw and/or interacted with the ad.^[54]^[55]

CPV (cost per view)[edit]

Cost per view video advertising. Both Google and TubeMogul endorsed this standardized CPV metric to the IAB's (Interactive Advertising Bureau) Digital Video Committee, and it's garnering a notable amount of industry support.^[56]

Other performance-based compensation[edit]

CPA (Cost Per Action or Cost Per Acquisition) or PPP (Pay Per Performance) advertising means the advertiser pays for the number of users who perform a desired activity, such as completing a purchase or filling out a registration form. Performance-based compensation can also incorporate revenue sharing, where publishers earn a percentage of the advertiser's profits made as a result of the ad. Performance-based compensation shifts the risk of failed advertising onto publishers.^[51]^{:4, 16}

Fixed cost[edit]

Fixed cost compensation means advertisers pay a fixed cost for delivery of ads online, usually over a specified time period, irrespective of the ad's visibility or users' response to it.

Benefits of Online Advertising[edit]

Cost[edit]

The low costs of electronic communication reduce the cost of displaying online advertisements compared to offline ads. Online advertising, and in particular social media, provides a low-cost means for advertisers to engage with large established communities.^[43] Advertising online offers better returns than in other media.^[51]^:1

Measurability[edit]

Online advertisers can collect data on their ads' effectiveness, such as the size of the potential audience or actual audience response,^[19]^:119 how a visitor reached their advertisement, whether the advertisement resulted in a sale, and whether an ad actually loaded within a visitor's view.^[48]^[49]^:59 This helps online advertisers improve their ad campaigns over time.

Formatting[edit]

Advertisers have a wide variety of ways of presenting their promotional messages, including the ability to convey images, video, audio, and links. Unlike many offline ads, online ads also can be interactive.^[18] For example, some ads let users input queries^[57] or let users follow the advertiser on social media.^[58] Online ads can even incorporate games.^[59]

Targeting[edit]

Publishers can offer advertisers the ability to reach customizable and narrow market segments for targeted advertising. Online advertising may use geo-targeting to display relevant advertisements to the user's geography. Advertisers can customize each individual ad to a particular user based on the user's previous preferences.^[26] Advertisers can also track whether a visitor has already seen a particular ad in order to reduce unwanted repetitious exposures and provide adequate time gaps between exposures.^[60]

Coverage[edit]

Online advertising can reach nearly every global market, and online advertising influences offline sales.^[61]^[62]^[63]

Speed[edit]

Once ad design is complete, online ads can be deployed immediately. The delivery of online ads does not need to be linked to the publisher's publication schedule. Furthermore, online advertisers can modify or replace ad copy more rapidly than their offline counterparts.^[64]

Concerns[edit]

Banner blindness[edit]

Eye-tracking studies have shown that Internet users often ignore web page zones likely to contain display ads (sometimes called "banner blindness"), and this problem is worse online than in offline media.^[65] On the other hand, studies suggest that even those ads "ignored" by the users may influence the user subconsciously.^[66]

Fraud on the Advertiser[edit]

There are numerous ways that advertisers can be overcharged for their advertising. For example, click fraud occurs when a publisher or third parties click (manually or through automated means) on a CPC ad with no legitimate buying intent.^[67] For example, click fraud can occur when a competitor clicks on ads to deplete its rival's advertising budget, or when publishers attempt to manufacture revenue.^[67]

Click fraud is especially associated with pornography sites. In 2011, certain scamming porn websites launched dozens of hidden pages on each visitor's computer, forcing the visitor's computer to click on hundreds of paid links without the visitor's knowledge.^[68]

As with offline publications, online impression fraud can occur when publishers overstate the number of ad impressions they have delivered to their advertisers. To combat impression fraud, several publishing and advertising industry associations are developing ways to count online impressions credibly.^[69]^[70]

Technological variations[edit]

Heterogeneous clients[edit]

Because users have different operating systems, web browsers^[71] and computer hardware (including mobile devices and different screen sizes), online ads may appear to users differently from how the advertiser intended, or the ads may not display properly at all. A 2012 comScore study revealed that, on average, 31% of ads were not "in-view" when rendered, meaning they never had an opportunity to be seen.^[72] Rich media ads create even greater compatibility problems, as some developers may use competing (and exclusive) software to render the ads (see e.g. Comparison of HTML 5 and Flash).^[73]

Furthermore, advertisers may encounter legal problems if legally required information doesn't actually display to users, even if that failure is due to technological heterogeneity.^[74]^:i In the United States, the FTC has released a set of guidelines indicating that it's the advertisers' responsibility to ensure the ads display any required disclosures or disclaimers, irrespective of the users' technology.^[74]^:4–8

Ad-blocking[edit]

Ad-blocking, or ad filtering, means the ads do not appear to the user because the user uses technology to screen out ads. Many browsers block unsolicited pop-up ads by default.^[75]Other software programs or browser add-ons may also block the loading of ads, or block elements on a page with behaviors characteristic of ads (e.g. HTML autoplay of both audio and video). Approximately 9% of all online page views come from browsers with ad-blocking software installed,^[76] and some publishers have 40%+ of their visitors using ad-blockers.^[3]

Anti-targeting technologies[edit]

Some web browsers offer privacy modes where users can hide information about themselves from publishers and advertisers. Among other consequences, advertisers can't use cookies to serve targeted ads to private browsers. Most major browsers have incorporated Do Not Track options into their browser headers, but the regulations currently are only enforced by the honor system.^[77]^[78]^[79]

Privacy Concerns[edit]

The collection of user information by publishers and advertisers has raised consumer concerns about their privacy.^[27]^[49] Sixty percent of Internet users would use Do Not Track technology to block all collection of information if given an opportunity.^[80]^[81] Over half of all Google and Facebook users are concerned about their privacy when using Google and Facebook, according to Gallup.^[82]

Many consumers have reservations about by online behavioral targeting. By tracking users' online activities, advertisers are able to understand consumers quite well. Advertisers often use technology, such as web bugs and respawning cookies, to maximizing their abilities to track consumers.^[49]^:60^[83]^[84] According to a 2011 survey conducted by Harris Interactive, over half of Internet users had a negative impression of online behavioral advertising, and forty percent feared that their personally-identifiable information had been shared with advertisers without their consent.^[85]^[86] Consumers can be especially troubled by advertisers targeting them based on sensitive information, such as financial or health status.^[83]

Trustworthiness of advertisers[edit]

Scammers can take advantage of consumers' difficulties verifying an online persona's identity,^[87]^:1 leading to artifices like phishing (where scam emails look identical to those from a well-known brand owner)^[88] and confidence schemes like the Nigerian "419" scam.^[89]^[90]^[91] The Internet Crime Complaint Center received 289,874 complaints in 2012, totaling over half a billion dollars in losses, most of which originated with scam ads.^[92]^[93]

Consumers also face malware risks when interacting with online advertising. Cisco's 2013 Annual Security Report revealed that clicking on ads was 182 times more likely to install a virus on a user's computer than surfing the Internet for porn.^[94]^[95]

Spam[edit]

The Internet's low cost of disseminating advertising contributes to spam, especially by large-scale spammers. Numerous efforts have been undertaken to combat spam, ranging from blacklists to regulatorily-required labeling to content filters, but most of those efforts have adverse collateral effects, such as mistaken filtering.^[5]

Regulation[edit]

In general, consumer protection laws apply equally to online and offline activities.^[74]^:i However, there are questions over which jurisdiction's laws apply and which regulatory agencies have enforcement authority over transborder activity.^[96]

As with offline advertising, industry participants have undertaken numerous efforts to self-regulate and develop industry standards or codes of conduct. Several United States advertising industry organizations jointly published Self-Regulatory Principles for Online Behavioral Advertising based on standards proposed by the FTC in 2009.^[97] European ad associations published a similar document in 2011.^[98] Primary tenets of both documents include consumer control of data transfer to third parties, data security, and consent for collection of certain health and financial data.^[97]^:2–4 Neither framework, however, penalizes violators of the codes of conduct.^[99]

Privacy and Data Collection[edit]

Privacy regulation can require users' consent before an advertiser can track the user or communicate with the user. However, affirmative consent ("opt in") can be difficult and expensive to obtain.^[49]^:60 Industry participants often prefer other regulatory schemes.

Different jurisdictions have taken different approaches to privacy issues with advertising. The United States has specific restrictions on online tracking of children in the Children's Online Privacy Protection Act (COPPA),^[97]^:16–17 and the FTC has recently expanded its interpretation of COPPA to include requiring ad networks to obtain parental consent before knowingly tracking kids.^[100] Otherwise, the U.S. Federal Trade Commission frequently supports industry self-regulation, although increasingly it has been undertaking enforcement actions related to online privacy and security.^[101] The FTC has also been pushing for industry consensus about possible Do Not Track legislation.

In contrast, the European Union's "Privacy and Electronic Communications Directive" restricts websites' ability to use consumer data much more comprehensively. The EU limitations restrict targeting by online advertisers; researchers have estimated online advertising effectiveness decreases on average by around 65% in Europe relative to the rest of the world.^[49]^:58

Delivery methods[edit]

Many laws specifically regulate the ways online ads are delivered. For example, online advertising delivered via email is more regulated than the same ad content delivered via banner ads. Among other restrictions, the U.S. CAN-SPAM Act of 2003 requires that any commercial email provide an opt-out mechanism.^[96] Similarly, mobile advertising is governed by the Telephone Consumer Protection Act of 1991 (TCPA), which (among other restrictions) requires user opt-in before sending advertising via text messaging.

The History of Catering

2014-09-15T06:26:00.003-07:00

Catering

A professionally catered event

Catering is the business of providing food service at a remote site or a site such as a hotel, public house (pub), or other location.

Mobile catering[edit]

Main article: Mobile catering

A mobile caterer serves food directly from a vehicle, cart or truck which is designed for the purpose. Mobile catering is common at outdoor events (such as concerts), workplaces, and downtown business districts.

Event catering[edit]

With such a large variety of catering available it is difficult to decide on which is the best for your guests.

Events range from cheese lunch drop-off to full-service catering. Caterers and their staff are part of the foodservice industry. Catering services provided vary depending on the event and can include: cooking and delivering food to an outside location; cooking, delivering and serving food; and full-service (preparing food, providing service staff, decoration of event location, prep and clean-up). In some cases of full-service catering, the caterer is called an event managing company.

When most people refer to a "caterer", they are referring to an event caterer who serves food with waiting staff at dining tables or sets up a self-serve buffet. The food may be prepared on site, i.e., made completely at the event, or the caterer may choose to bring prepared food and put the finishing touches on once it arrives.

The event caterer staff are not responsible for preparing the food but often help set up the dining area. This service is typically provided at banquets, conventions, and weddings. Any event where all who attend are provided with food and drinks or sometimes only hors d'oeuvres is often called a catered event.

Many events require working with an entire theme or color scheme. A catering company or specialist is expected to know how to prepare food and to make it attractive. As such, certain catering companies have moved toward a full-service business model commonly associated with event planners. They take charge of not only food preparation but also decorations, such as table settings and lighting.

The trend is towards satisfying all the clients senses with food as a focal point. With the correct atmosphere, professional event caterers with experience can make an event special and memorable.

Beautifully prepared food alone can appeal to the senses of taste, smell, and sight - perhaps even touch, but the decorations and ambiance can play a significant part in a successfully catered event.

Catering is often sold on a per-person basis, meaning that there is a flat price for each additional person. However, things like lighting and fire permits are not scaled with the guest count, so per-person pricing is not always appropriate. It is necessary to keep the cost of the food and supplies below a price margin in order to make a profit on the catering.

As many others in the food service industry, caterers and their staff work long hours. It is not uncommon for them to work on holidays or 7 days a week during holiday event seasons.

A comprehensive, formal full-service catering proposal is likely to include the following time-line matters:

Rental arrival time
Staff arrival time
Bar open time
Meal serve time
Bar close time
Rental pickup
Out-of-venue time

Each of these factors affects the catering price.

For example, a rental quote for an "anytime" weekday delivery is usually much more economical than an "exact-time" delivery.

General menu considerations: Clients may have specific dietary or religious needs to consider. these include Halal, Kosher, Vegetarian, Vegan and food allergy requests. Increasingly, clients are interested in food sustainability and food safety.
Hors d'oeuvres: it should be clear if these are passed or stationary. Most caterers agree that three or four passed items are appropriate for the one-hour period prior to a meal.
Meal Rentals: May include tables, chairs, dance floor, plants, tabletop (china, flatware, glassware, linens, chargers), bar glassware, serving equipment, salt/peppers, etc. It should be clear whether table and chair setup and take-down is included. Most rental companies do not automatically include setup and take-down in the rental charges.
Labor: varies from caterer to caterer, but generally speaking, an event will have a Lead/Captain/Event Manager, a Chef, perhaps a Sous Chef or Kitchen Assistant, Wait staff and Bartenders. The labor on a plated dinner is generally much higher than the labor on a buffet, because a plated dinner involves double the china, and usually a minimum of three served courses, plus served coffee. Simply put, there's a lot more to do. To do it properly requires roughly 10 to 50% more staff. On a large event, this can be substantial, especially if overtime or doubletime applies.
Service Charge: Sales Tax, Some quotes will include lighting,liquor permit, fire permits, draping, florals, valet and coat check. Many venues discreetly get a "cut" of the catering bill. Caterers are contractually committed to not disclose this fee specifically in their contracts with the clients. Therefore, catering will sometimes cost substantially more at one venue versus another. Also, caterers must compete with illegal operators. A legitimate caterer will have a business license and a health permit both showing the address of the place from which they do business.

In addition, many caterers will provide partial catering services in addition to full-service. Partial catering can include cooking and delivery of prepared foods, pre-cooked dishes for pickup at the caterer's location, and cooking, delivery and setup without service. In many cases partial catering can be an excellent and economical option to full-service catering.

Increasingly, restaurants are providing catering menus and services in addition to their regular menus. Restaurant catering can be either on-site or off-site, depending on the services offered.

Boxed lunch catering[edit]

A box lunch is a lunch consisting of a sandwich, chips, fruit and a dessert. A box lunch is typically prepared by a caterer and dropped off to a location for a client’s dining needs. Box lunches are used primarily in the corporate arena for working lunches when they do not have time to take a break from their meeting yet still need to eat. A box lunch order is placed with a caterer a couple of days before the delivery date and is a cheaper way to go instead of a full sit-down lunch. The box lunch option is strictly a drop-off service and does not offer any type of wait staff or cleanup. The caterer’s only job is to prepare and deliver the food. In some cases, the caterer can set up the food, which means placing the individual cartons on a table or another area that is easily accessible to the clients. A box lunch is prepared for each person, so that they have all of their food in one container. This makes for very quick efficient service. Caterers can offer a variety of sandwiches such as:

Roast Beef
Turkey
Ham
Egg
Tuna Salad
Chicken
Chicken Salad
Vegetarian

The box lunch will also include an individual pack of chips/crisps, a piece of fruit and a dessert such as a Cookie or a Brownie. Drinks such as sodas, waters and juices will also be dropped off by the caterer in individual containers, but may or may not be included in the box lunch itself. The idea is for the clients to be able to grab their box and a drink and go. The boxes or bags should be visibly marked with the type of sandwich included or grouped together for easy identification. The individual bags and boxes allow guests to dispose of their trash at their leisure and keep everything neat and clean. For example, if a company is holding their lunch meeting in a conference room, it is necessary that they can clean up easily. Every individual can simply place all of their trash back into the box or bag to clean up. The latest in off site catering services is Vegan catering.

Catering Officers on ships[edit]

Merchant ships often carry Catering Officers - especially ferries, cruise liners and large cargo ships. In fact, the term "catering" was in use in the world of the merchant marine long before it became established as a land-bound business.

Jayant parkash

The History of Visual basic

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Visual Basic

Contents

Language features[edit]

Characteristics[edit]

History[edit]

Timeline description[edit]

Derivative languages[edit]

Performance and other issues[edit]

Legacy development and support[edit]

Example code[edit]

The History of Mathematics

Mathematics

History

Evolution

Etymology

Definitions of mathematics

Inspiration, pure and applied mathematics, and aesthetics

Notation, language, and rigor

Fields of mathematics

Foundations and philosophy

Pure mathematics

Quantity

Structure

Space

Change

Applied mathematics

Statistics and other decision sciences

Computational mathematics

Mathematical awards

Mathematics as science

The History of Ceiling fan

Ceiling fan

Contents

History

Uses

Exception

Parts of a ceiling fan

Configurations

Operating a ceiling fan

Types of ceiling fans

Safety concerns with installation

Low-hanging fans/danger to limbs

MythBusters: "Killer Ceiling Fan"

Wobbling

Think about it!

The Master's Degree History

Master's degree

Titles[edit]

Types[edit]

Structure[edit]

Duration[edit]

Admission[edit]

Comparable European degrees[edit]

South America[edit]

Brazil[edit]

Asia[edit]

Hong Kong[edit]

MArch, MLA, MUD, MA, MSc, MSocSc, MSW, MEng, LLM[edit]

MPhil[edit]

Pakistan[edit]

India[edit]

Israel[edit]

Taiwan[edit]

Children's Day

Contents

Universal Children's Day[edit]

Dates around the world[edit]

Argentina[edit]

Armenia[edit]

Australia[edit]

Bangladesh[edit]

Bolivia[edit]

Brazil[edit]

Bulgaria[edit]

Canada[edit]

Central Africa[edit]

Chile[edit]