Computer Internet

Jejaring Sosial Lebih Candu Ketimbang Rokok

noreply@blogger.com (Beauty Schools) — Fri, 24 Feb 2012 23:13:00 +0000

Ilustrasi (Foto : Okezone.com)

BERLIN (KRjogja.com) - Jika keinginan Anda untuk tetap online selama 24 jam sepekan menimbulkan rasa kurang bertenaga, bisa jadi Anda kecanduan media sosial. Sebuah penelitian baru-baru ini mengungkap bahwa mengecek email dan media sosial ternyata lebih adiktif dari tembakau dan alkohol.

Seperti diwartakan ABC, Selasa (7/2/2012), sekelompok peneliti dari Booth Business School di Chicago University melakukan suatu eksperimen menggunakan perangkat BlackBery, untuk menguji hasrat sejumlah 205 orang di rentang usia 18 sampai 85 tahun, di Wurtzburg, Jerman.

Partisipan tersebut diberi pertanyaan selama tujuh kali sehari selama satu pekan, untuk mengidentifikasi hasrat yang mereka rasakan dan seberapa kuat hasrat tersebut. Kemudian, para peneliti tersebut menyaring ribuan respon untuk mencapai kesimpulannya.

Beruntung, ternyata penelitian tersebut menunjukkan bahwa kita belum jadi budak perangkat cerdas tersebut. Karena, kebutuhan untuk tidur dan beristirahat masih menempati urutan teratas di antara hasil penelitian itu.

Namun pada kategori "rata-rata kegagalan pengendalian diri", hasrat mengecek media sosial, email, dan pekerjaan berada di atas hasrat untuk menghisap rokok sambil menyesap segelas scotch.

"Meskipun ingin ditahan, hasrat terhadap media mungkin relatif lebih sulit dikendalikan karena tingkat ketersediaannya yang tinggi, dan untuk melakukannya pun terasa tidak memerlukan biaya besar," terang Wilhelm Hofmann yang memimpin kelompok peneliti tersebut.

"Rokok dan alkohol membutuhkan biaya lebih, seperti waktu dan uang, sedangkan kesempatan tidak selalu ada. Meskipun menyerahkan diri pada hasrat terhadap media terlihat minim risiko, sering menggunakannya tetap akan mencuri banyak waktu," tandasnya.

Kalah Fitur, Handphone China Makin Tersingkir

noreply@blogger.com (Beauty Schools) — Fri, 24 Feb 2012 23:06:00 +0000

Munculnya handphone merk Jepang dengan harga murah serta dilengkapi fitur-fitur layaknya handphone China ditengarai akan menggusur pasar handphone merk China di market DIY. Hal ini menyebabkan pasar handphone China tahun ini diperkirakan menurun hingga 30 persen.

Marketing Manajer Jogjatronik Mall, Poppy Chandra mengatakan pada 2010 lalu menjadi puncak membanjirnya handphone berbagai merk dari China di pasaran. Namun, tahun 2011 yang lalu penjualan handphone China mengalami penurunan dan terus anjlok hingga saat ini.

"Berbagai kelebihan fitur yang sering menyertai hape China ini menjadikan konsumen banyak yang memburunya seperti saat booming tahun 2010 silam. Berbagai merk China berlomba mengeluarkan produk dengan berbagai kelebihan
fitur namun dibanderol dengan harga yang sangat murah," ujarnya di Yogyakarta, Senin (6/2).

Poppy mengungkapkan dengan keluarnya handphone merk Jepang yang juga dibanderol dengan harga murah menyebabkan pembeli kembali melirik handphone merk Jepang. Gebrakan pabrikan Jepang seperti Nokia dan Samsung yang berani mengeluarkan produk dengan banderol harga murah memang cukup membuat pemain handphone China tersingkir.

"Pasar handphone China kini sudah mulai menurun kira-kira 20 hingga 30 persen. Sebelumnya, kehadiran handphone merk China memang menggerus pasar handphone Jepang seperti Nokia, Samsung, Sony Ericson ataupun beberapa merk lain yang telah eksis," paparnya.

Menurutnya tren penurunan ini juga terjadi karena konsumen handphone sekarang mulai mengerti bahwa meskipun dilengkapi dengan berbagai fitur unggulan dan dipasarkan dengan harga yang murah namun kualitas handphone China masih kalah dengan handphone pabrikan Jepang. Daya tahan yang kurang bersaing baik dari sisi cassing, spare part ataupun detil produk masih kalah dengan Jepang.

Produsen hape China, Mito yang berada di Yogyakarta mengaku adanya penurunan penjualan. Head of service Mito Yogyakarta, Heri mengatakan secara umum kondisi pasar handphone China memang sedang mengalami penurunan akibat handphone Jepang yang telah lama eksis mulai mengeluarkan produk seharga di bawah Rp 500 ribu. Tren penurunan ini sudah terjadi sejak tahun 2011 silam di mana pabrikan China sudah mulai mengurangi produknya, tidak banyak mengeluarkan produk sebanyak tahun sebelumnya.

"Tahun lalu rata-rata penjualan kami sekitar 3 ribu unit setiap bulannya. Salah satu strategi kami adalah dengan mengerem peluncuran produk, tetapi lebih menekankan pada kualitas barang yang dikeluarkan. Tahun ini kami mungkin hanya mengeluarkan sedikit produk, tetapi produk tersebut kualitasnya sangat terjamin," pungkasnya.

Efek Soft Tone pada Foto

noreply@blogger.com (Beauty Schools) — Fri, 21 May 2010 08:37:00 +0000

Saya sebenernya gak terlalu bisa nge-Tone.. hehehe.. tapi saya tadi coba-coba.. dan hasilnya lumayan Unik dan sop Soft.

Saya pernah liat ada fotografer yang hasil editannya kayak gini juga.

Gampang banget kok caranya.. pemula aja pasti bisa.. kecuali yang pemula banget.. yang pegang komputer aja baru sekali.. hehehe.. tapi gak mungkin deng.. yang baca ini kan lagi buka Ilmuphotoshop, berarti udah pegang komputer puluhan bahkan ratusan kali kan ?

Pertamax buka foto yang akan diedit.. usahakan foto nya yang outdoor yah..kalo agak gelap fotonya di terangin dulu aja pake Image > adjustment > brightness/contrass

Lagi-lagi saya pake foto adik saya.. abis cuman keluarga aja yang jadi objek foto saya.. kecuali ada yang dengan sukarela mau difoto hehehe.. ada yang mau ?

syaratnya fotogenik, suara bagus, bisa nyanyi.. yee.. ini teh mau kontes Indonesian Idol apa mau difoto ? hihihi..

Sekarang Tekan CTRL + J untuk menduplikat layer background

Klik Channel Palette ( kita maen-maen channel )

Pilih channel Green.. tekan CTRL + A ( select all) dan CTRL + C untuk copy yang terseleksi

Klik Channel Blue dan tekan CTRL + V untuk paste channel green tadi

sekarang klik channel RGB .. gambar sudah berubah kan ?

Kita kembali ke Layer dengan menekan Layer palette

hasilnya :

Klik New Adjustment yang letaknya dibawah jendela layer palette > pilih Selective Kolor Color

Setting seperti ini yah :

Ubah opacity dan fill menjadi masing-masing 50%

Sekarang kita add New Adjustment lagi.. Klik New Adjustment > Channel Mixer

Setting seperti gambar dibawah :

gampang kan ? Nih hasilnya gan…

Silahkan test angka-angka nya.. pasti bisa dapet tone yang lebih keren lagi..

Selamat Mencoba..

Microsoft Faces New Browser Foe in Google

noreply@blogger.com (Beauty Schools) — Wed, 24 Sep 2008 07:42:00 +0000

By STEVE LOHR
Published: September 1, 2008
The browser war is back on.

Scott McCloud/Google
Google released a comic book to announce Chrome, which is partly based on an open-source rendering engine, WebKit.

This time, Microsoft’s opponent is Google, a familiar foe.
On Tuesday, Google will release a free Web browser called Chrome that the company said would challenge Microsoft’s Internet Explorer, as well as the Firefox browser.
The browser is a universal doorway to the Internet, and the use of Internet software and services is rapidly growing. Increasingly, the browser is also the doorway to the Web on cellphones and other mobile devices, widening the utility of the Web and Web advertising. Google, analysts say, cannot let Microsoft’s dominant share of the browser market go without a direct challenge.
Google already competes with Microsoft in online search and Internet advertising. They both make operating software for cellphones. Google is increasingly competing with Microsoft head-on in software that handles basic productivity like word processing, spreadsheet, presentation and e-mail programs. Google has Web-based software in these markets that are low-cost or free alternatives to Microsoft’s lucrative desktop software.
Despite the frequent clashes with Microsoft — including the role Google played in thwarting an attempted acquisition of Yahoo — Google has come out on top only in search and search advertising. But Google does not have to win the browser war. Strategically, opening yet another front against Microsoft forces it to divert resources to defend franchises.
Now, Chrome heightens the rivalry and marks a shift for Google, which has strongly backed Firefox, the open-source browser that has gained about a fifth of the market against the dominant Internet Explorer.
Google’s browser project has been under way for more than a year, a person close to the company said.
In a brief statement, Microsoft welcomed the new entry and expressed confidence that people would prefer Explorer, which is on every Windows PC sold.
“The browser landscape is highly competitive,” said Dean Hachamovitch, general manager of the Internet Explorer group. “But people will choose Internet Explorer 8 for the way it puts the services they want right at their fingertips, respects their personal choices about how they want to browse and, more than any other browsing technology, puts them in control of their personal data online.”
Google has clashed with Microsoft before, saying it had designed IE to gain ground in search, a market where Google is the runaway leader.
After Microsoft introduced IE 7 in 2006, Google complained that the browser’s search box favored Microsoft’s search service. Microsoft responded and made modifications, and a federal judge overseeing the antitrust consent decree against Microsoft determined that the browser design was not anticompetitive.
The first round of the browser wars in the 1990s led to a sweeping federal antitrust suit against Microsoft for the tactics it used to stifle competition from the commercial pioneer in browsing software, Netscape Communications. A federal appeals court ruled in 2001 that Microsoft had repeatedly violated the nation’s antitrust laws. Microsoft later reached a settlement with the Bush administration, which included some sanctions but left the company free to bundle browsing software with Windows, which runs more than 90 percent of all personal computers.
Microsoft recently stepped up its own browser development efforts, given the increasing importance of the browser and signs that Firefox is nibbling at its lead. Microsoft released a new version, IE8, last week to generally favorable reviews.
Microsoft still holds 73 percent of the browser market, according to Net Applications, a research firm. The market share for Firefox has climbed to 19 percent, while Apple’s Safari has 6 percent.
Chrome also puts Google in competition with an ally, the Mozilla Corporation, which manages the Firefox project. Just last week, Google renewed its deal with Mozilla. Under the arrangement, Google Search is the home page for Firefox and Google is its default search bar, and Google makes substantial payments to Mozilla. The agreement runs through November 2011, and will continue.
Google’s cooperation with Mozilla, however friendly, meant that it was ceding control of the Internet’s vital gateway technology — and the dominant supplier of that technology is its archrival, Microsoft.
Given the increasing importance of the browser and its widening competition with Microsoft, Google’s entry into the market is not surprising, said John Lilly, chief executive of Mozilla.
“It would be more surprising to me if Google didn’t do something in the browser space,” Mr. Lilly said. “After all, Google is 100 percent on the Web.”
Google’s move, he said, would put “more competitive pressure on us to keep coming up with great browser technology. But having more smart people competing to improve browser technology and the user experience is a good thing.”

Mr. Lilly also noted that Mozilla, while a private company, is entirely owned by the Mozilla Foundation. The browser project was begun to provide an alternative to Microsoft’s browser. “The mission of Mozilla is to keep the Web open, a pure public benefit,” he said. “Others have other motivations and Google’s move also serves to highlight our position in the marketplace.”
Chrome will be available to download in a test, or beta, version on Tuesday, Google announced on its Web site Monday afternoon. The browser will run on Windows. Google is also working on Chrome versions for Apple’s Macintosh, as well as Linux, an open source operating system.
In a curious twist, Google made its online announcement after its plans appeared as a digital “comic book” that was posted by Google Blogoscoped, a Web site that tracks the Internet search giant.
According to Google’s Web site post, by Sundar Pichai, an engineering director and vice president for product management, Chrome is designed for speed and ease of use.
But the other design goal, it seems, was to make sure Google could control how well the growing range of Web-based software it is developing will perform, instead of having to run on a Microsoft browser.
“Under the hood,” Mr. Pichai wrote, “we were able to build the foundation of a browser that runs today’s complex Web applications much better.”
Later, he wrote, “we improved speed and responsiveness across the board. We also built a more powerful JavaScript engine, V8, to power the next generation of Web applications that aren’t even possible in today’s browsers.”
Chrome is based on an open-source rendering engine, WebKit, and an open-source version of Google’s Gears technology. Chrome will also be able to run in a privacy mode, InCognito, so that no information about a person’s browsing is collected. With IE8 last week, Microsoft added a privacy mode of browsing, called InPrivate.
The privacy features, analysts note, could undercut the Internet advertising business of Google, but also Microsoft, Yahoo and others that depend on ads aimed at users based on their browsing behavior. But it is unclear, analysts say, how large a share of users will opt for the privacy browsing mode and give up the convenience of having a browser store sites recently visited in tabbed settings for easy navigation.

Firefox Browser

noreply@blogger.com (Beauty Schools) — Fri, 15 Aug 2008 09:18:00 +0000

Firefox is a free open-source web browser developed by Mozilla.

What is Firefox?

Firefox is a free, open-source web browser for Windows, Linux and Mac. It is small and fast and offers many new features like popup blocking and tabbed browsing.

Firefox is based on the Mozilla code, and is one of the most standards-compliant browsers available.

Firefox is available for Windows 98, Windows 2000, Windows XP, Windows Vista, Mac OS X, and Linux.

Firefox 3

Mozilla's latest version of their browser, Firefox 3, was released on June 17th. 2008.

Firefox 3 has dozens of new features, such as Password Manager, One-Click Bookmarking, Smart Location and more.

One feature that was important for Mozilla, was the Improved Performance. Firefox 3 lets you view web pages faster, using less of your computer's memory.

What is Mozilla?

Mozilla is an open-source web development project.

The Mozilla Application Suite (also known as SeaMonkey) is a complete set of web applications; a browser, a mail client, a news client, a chat client and more.

Firefox is just a browser. With Firefox you cannot chat or read emails or news. This makes it smaller, faster and easier to use (but makes chat, email and news harder to use?).

You can read about Mozilla in the previous chapter.

Firefox And Mozilla

Firefox was previously called Mozilla Firebird (which was previously called Phoenix, which was previously called Mozilla).

The confusing name changes have something to do with legal issues (I think). You can read more about the Mozilla name changes in the previous chapter.

It is expected that Firefox will be used as the default browser in a future version of the Mozilla Suite.

Firefox Features

Firefox has automatic Popup Blocking. This if fine for stopping annoying popup ads, but not so good for sites using popup windows in a good way.

Tabbed Browsing is a modern and time saving feature. It makes it possible to view many web pages in one browser window.

Google Search with auto complete is built into Firefox's tool bar.

Keywords for bookmarks with quick searches (e.g., type "goo xml tutorial" into the location bar and get a Google search page on "xml tutorial" in one step).

Dictionary Tooltip - double-click any word to see its definition.

Firefox has Improved Security. It is not integrated with the operating system and does not support ActiveX controls and VBScripts (features known to have security holes).

A built-in modern Download Manager downloads files in the background to the desktop.

Firefox has Customizable Toolbars, allowing users to add and remove items as well as create new toolbars.

With the Theme Manager, the users can change the look and feel of Firefox.

Firefox keeps itself up-to-date. Smart Update searches for updates in the background and informs the user about available updates.

From: www.w3schools.com

Internet

noreply@blogger.com (Beauty Schools) — Sat, 02 Aug 2008 09:12:00 +0000

From Wikipedia, the free encyclopedia

Visualization of the various routes through a portion of the Internet.

Internet portal

The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol (IP) Suite. It is a "network of networks" that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.

The Internet carries various information resources and services, such as electronic mail, online chat, file transfer and file sharing, online gaming, and the inter-linked hypertext documents and other resources of the World Wide Web (WWW).

Terminology

The terms "Internet" and "World Wide Web" are often used in every-day speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is the global data communications backbone, i.e., the hardware and software infrastructure, that provides connectivity between resources or services and the users of such facilities. In contrast, the Web is one of the services communicated via the Internet. It is a collection of interconnected documents and other resources, linked by symbolic hyperlinks and URLs.

History

Creation

The USSR's launch of Sputnik spurred the United States to create the Advanced Research Projects Agency, known as ARPA, in February 1958 to regain a technological lead.^[1]^[2] ARPA created the Information Processing Technology Office (IPTO) to further the research of the Semi Automatic Ground Environment (SAGE) program, which had networked country-wide radar systems together for the first time. J. C. R. Licklider was selected to head the IPTO, and saw universal networking as a potential unifying human revolution.

Licklider moved from the Psycho-Acoustic Laboratory at Harvard University to MIT in 1950, after becoming interested in information technology. At MIT, he served on a committee that established Lincoln Laboratory and worked on the SAGE project. In 1957 he became a Vice President at BBN, where he bought the first production PDP-1 computer and conducted the first public demonstration of time-sharing.

At the IPTO, Licklider recruited Lawrence Roberts to head a project to implement a network, and Roberts based the technology on the work of Paul Baran,^{[citation needed]} who had written an exhaustive study for the U.S. Air Force that recommended packet switching (as opposed to circuit switching) to make a network highly robust and survivable. After much work, the first two nodes of what would become the ARPANET were interconnected between UCLA and SRI International in Menlo Park, California, on October 29, 1969. The ARPANET was one of the "eve" networks of today's Internet. Following on from the demonstration that packet switching worked on the ARPANET, the British Post Office, Telenet, DATAPAC and TRANSPAC collaborated to create the first international packet-switched network service. In the UK, this was referred to as the International Packet Stream Service (IPSS), in 1978. The collection of X.25-based networks grew from Europe and the US to cover Canada, Hong Kong and Australia by 1981. The X.25 packet switching standard was developed in the CCITT (now called ITU-T) around 1976. X.25 was independent of the TCP/IP protocols that arose from the experimental work of DARPA on the ARPANET, Packet Radio Net and Packet Satellite Net during the same time period. Vinton Cerf and Robert Kahn developed the first description of the TCP protocols during 1973 and published a paper on the subject in May 1974. Use of the term "Internet" to describe a single global TCP/IP network originated in December 1974 with the publication of RFC 675, the first full specification of TCP that was written by Vinton Cerf, Yogen Dalal and Carl Sunshine, then at Stanford University. During the next nine years, work proceeded to refine the protocols and to implement them on a wide range of operating systems.

The first TCP/IP-wide area network was made operational by January 1, 1983 when all hosts on the ARPANET were switched over from the older NCP protocols to TCP/IP. In 1985, the United States' National Science Foundation (NSF) commissioned the construction of a university 56 kilobit/second network backbone using computers called "fuzzballs" by their inventor, David L. Mills. The following year, NSF sponsored the development of a higher-speed 1.5 megabit/second backbone that became the NSFNet. A key decision to use the DARPA TCP/IP protocols was made by Dennis Jennings, then in charge of the Supercomputer program at NSF.

The opening of the network to commercial interests began in 1988. The US Federal Networking Council approved the interconnection of the NSFNET to the commercial MCI Mail system in that year and the link was made in the summer of 1989. Other commercial electronic e-mail services were soon connected, including OnTyme, Telemail and Compuserve. In that same year, three commercial Internet service providers (ISP) were created: UUNET, PSINET and CERFNET. Important, separate networks that offered gateways into, then later merged with, the Internet include Usenet and BITNET. Various other commercial and educational networks, such as Telenet, Tymnet, Compuserve and JANET were interconnected with the growing Internet. Telenet (later called Sprintnet) was a large privately funded national computer network with free dial-up access in cities throughout the U.S. that had been in operation since the 1970s. This network was eventually interconnected with the others in the 1980s as the TCP/IP protocol became increasingly popular. The ability of TCP/IP to work over virtually any pre-existing communication networks allowed for a great ease of growth, although the rapid growth of the Internet was due primarily to the availability of commercial routers from companies such as Cisco Systems, Proteon and Juniper, the availability of commercial Ethernet equipment for local-area networking and the widespread implementation of TCP/IP on the UNIX operating system.

Growth

Although the basic applications and guidelines that make the Internet possible had existed for almost a decade, the network did not gain a public face until the 1990s. On August 6, 1991, CERN, which straddles the border between France and Switzerland, publicized the new World Wide Web project. The Web was invented by English scientist Tim Berners-Lee in 1989.

An early popular web browser was ViolaWWW, based upon HyperCard. It was eventually replaced in popularity by the Mosaic web browser. In 1993, the National Center for Supercomputing Applications at the University of Illinois released version 1.0 of Mosaic, and by late 1994 there was growing public interest in the previously academic, technical Internet. By 1996 usage of the word Internet had become commonplace, and consequently, so had its use as a synecdoche in reference to the World Wide Web.

Meanwhile, over the course of the decade, the Internet successfully accommodated the majority of previously existing public computer networks (although some networks, such as FidoNet, have remained separate). During the 1990s, it was estimated that the Internet grew by 100% per year, with a brief period of explosive growth in 1996 and 1997.^[3] This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary open nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over the network.^{[citation needed]}

University students' appreciation and contributions

New findings in the field of communications during the 1960s, 1970s and 1980s were quickly adopted by universities across North America.

Examples of early university Internet communities are Cleveland FreeNet, Blacksburg Electronic Village and NSTN in Nova Scotia.^[4] Students took up the opportunity of free communications and saw this new phenomenon as a tool of liberation. Personal computers and the Internet would free them from corporations and governments (Nelson, Jennings, Stallman).

Graduate students played a huge part in the creation of ARPANET. In the 1960s, the network working group, which did most of the design for ARPANET's protocols, was composed mainly of graduate students.

Today's Internet

The My Opera Community server rack. From the top, user file storage (content of files.myopera.com), "bigma" (the master MySQL database server), and two IBM blade centers containing multi-purpose machines (Apache front ends, Apache back ends, slave MySQL database servers, load balancers, file servers, cache servers and sync masters).

Aside from the complex physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe how to exchange data over the network. Indeed, the Internet is defined by its interconnections and routing policies.

As of March 31, 2008, 1.407 billion people use the Internet according to Internet World Stats.^[5]

Internet protocols

The complex communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. While the hardware can often be used to support other software systems, it is the design and the rigorous standardization process of the software architecture that characterizes the Internet.

The responsibility for the architectural design of the Internet software systems has been delegated to the Internet Engineering Task Force (IETF).^[6] The IETF conducts standard-setting work groups, open to any individual, about the various aspects of Internet architecture. Resulting discussions and final standards are published in Request for Comments (RFCs), freely available on the IETF web site.

The principal methods of networking that enable the Internet are contained in a series of RFCs that constitute the Internet Standards. These standards describe a system known as the Internet Protocol Suite. This is a model architecture that divides methods into a layered system of protocols (RFC 1122, RFC 1123). The layers correspond to the environment or scope in which their services operate. At the top is the space (Application Layer) of the software application, e.g., a web browser application, and just below it is the Transport Layer which connects applications on different hosts via the network (e.g., client-server model). The underlying network consists of two layers: the Internet Layer which enables computers to connect to one-another via intermediate (transit) networks and thus is the layer that establishes internetworking and the Internet, and lastly, at the bottom, is a software layer that provides connectivity to hosts on the same local link (therefor called Link Layer), e.g., a local area network (LAN) or a dial-up connection. This model is also known as the TCP/IP model of networking. While other models have been developed, such as the Open Systems Interconnect (OSI) model, they are not compatible in the details of description, nor implementation.

The most prominent component of the Internet model is the Internet Protocol (IP) which facilitates the internetworking of networks. IP Version 4 (IPv4) is the initial version used on the first generation of the today's Internet and is still in dominant use. It was designed to address up to ~4.3 billion (10⁹) Internet hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion. A new protocol version was developed, IPv6, which provides vastly larger addressing capabilities and more efficient routing of traffic. IPv6 is currently in commercial deployment phase around the world.

IPv6 is not interoperable with IPv4. It essentially establishes a "parallel" version of the Internet not accessible with IPv4 software. This means software upgrades are necessary for every networking device that needs to communication on the IPv6 Internet. Most modern computer operating systems are already fully converted to operate with both version of the Internet Protocol, however, network infrastructures are still lagging in this development.

Internet structure

There have been many analyses of the Internet and its structure. For example, it has been determined that the Internet IP routing structure and hypertext links of the World Wide Web are examples of scale-free networks.

Similar to the way the commercial Internet providers connect via Internet exchange points, research networks tend to interconnect into large subnetworks such as the following:

GEANT
GLORIAD
The Internet2 Network (formally known as the Abilene Network)
JANET (the UK's national research and education network)

These in turn are built around relatively smaller networks. See also the list of academic computer network organizations.

In network diagrams, the Internet is often represented by a cloud symbol, into and out of which network communications can pass.

ICANN

ICANN headquarters in Marina Del Rey, California, United States

The Internet Corporation for Assigned Names and Numbers (ICANN) is the authority that coordinates the assignment of unique identifiers on the Internet, including domain names, Internet Protocol (IP) addresses, and protocol port and parameter numbers. A globally unified namespace (i.e., a system of names in which there is at most one holder for each possible name) is essential for the Internet to function. ICANN is headquartered in Marina del Rey, California, but is overseen by an international board of directors drawn from across the Internet technical, business, academic, and non-commercial communities. The US government continues to have the primary role in approving changes to the root zone file that lies at the heart of the domain name system. Because the Internet is a distributed network comprising many voluntarily interconnected networks, the Internet has no governing body. ICANN's role in coordinating the assignment of unique identifiers distinguishes it as perhaps the only central coordinating body on the global Internet, but the scope of its authority extends only to the Internet's systems of domain names, IP addresses, protocol ports and parameter numbers.

On November 16, 2005, the World Summit on the Information Society, held in Tunis, established the Internet Governance Forum (IGF) to discuss Internet-related issues.

Language

The prevalent language for communication on the Internet is English. This may be a result of the Internet's origins, as well as English's role as a lingua franca. It may also be related to the poor capability of early computers, largely originating in the United States, to handle characters other than those in the English variant of the Latin alphabet.

After English (30% of Web visitors) the most requested languages on the World Wide Web are Chinese (17%), Spanish (9%), Japanese (7%), French (5%) and German (5%).^[7]

By continent, 38% of the world's Internet users are based in Asia, 27% in Europe, 18% in North America, 10% in Latin America and the Caribbean, and 7% in Australia.^[5]

The Internet's technologies have developed enough in recent years, especially in the use of Unicode, that good facilities are available for development and communication in most widely used languages. However, some glitches such as mojibake (incorrect display of foreign language characters, also known as kryakozyabry) still remain.

Internet and the workplace

The Internet is allowing greater flexibility in working hours and location, especially with the spread of unmetered high-speed connections and Web applications.

The Internet viewed on mobile devices

The Internet can now be accessed virtually anywhere by numerous means. Mobile phones, datacards, handheld game consoles and cellular routers allow users to connect to the Internet from anywhere there is a cellular network supporting that device's technology.

Within the limitations imposed by the small screen and other limited facilities of such a pocket-sized device, all the services of the Internet, including email and web browsing, may be available in this way. Service providers may restrict the range of these services and charges for data access may be significant, compared to home usage.

Common uses

E-mail

The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Even today it can be important to distinguish between Internet and internal e-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks and machines out of both the sender's and the recipient's control. During this time it is quite possible for the content to be read and even tampered with by third parties, if anyone considers it important enough. Purely internal or intranet mail systems, where the information never leaves the corporate or organization's network, are much more secure, although in any organization there will be IT and other personnel whose job may involve monitoring, and occasionally accessing, the e-mail of other employees not addressed to them.

The World Wide Web

Graphic representation of a minute fraction of the WWW, demonstrating hyperlinks

Many people use the terms Internet and World Wide Web (or just the Web) interchangeably, but, as discussed above, the two terms are not synonymous.

The World Wide Web is a huge set of interlinked documents, images and other resources, linked by hyperlinks and URLs. These hyperlinks and URLs allow the web servers and other machines that store originals, and cached copies, of these resources to deliver them as required using HTTP (Hypertext Transfer Protocol). HTTP is only one of the communication protocols used on the Internet.

Web services also use HTTP to allow software systems to communicate in order to share and exchange business logic and data.

Software products that can access the resources of the Web are correctly termed user agents. In normal use, web browsers, such as Internet Explorer and Firefox, access web pages and allow users to navigate from one to another via hyperlinks. Web documents may contain almost any combination of computer data including graphics, sounds, text, video, multimedia and interactive content including games, office applications and scientific demonstrations.

Through keyword-driven Internet research using search engines like Yahoo! and Google, millions of people worldwide have easy, instant access to a vast and diverse amount of online information. Compared to encyclopedias and traditional libraries, the World Wide Web has enabled a sudden and extreme decentralization of information and data.

Using the Web, it is also easier than ever before for individuals and organisations to publish ideas and information to an extremely large audience. Anyone can find ways to publish a web page, a blog or build a website for very little initial cost. Publishing and maintaining large, professional websites full of attractive, diverse and up-to-date information is still a difficult and expensive proposition, however.

Many individuals and some companies and groups use "web logs" or blogs, which are largely used as easily updatable online diaries. Some commercial organisations encourage staff to fill them with advice on their areas of specialization in the hope that visitors will be impressed by the expert knowledge and free information, and be attracted to the corporation as a result. One example of this practice is Microsoft, whose product developers publish their personal blogs in order to pique the public's interest in their work.

Collections of personal web pages published by large service providers remain popular, and have become increasingly sophisticated. Whereas operations such as Angelfire and GeoCities have existed since the early days of the Web, newer offerings from, for example, Facebook and MySpace currently have large followings. These operations often brand themselves as social network services rather than simply as web page hosts.

Advertising on popular web pages can be lucrative, and e-commerce or the sale of products and services directly via the Web continues to grow.

In the early days, web pages were usually created as sets of complete and isolated HTML text files stored on a web server. More recently, websites are more often created using content management system (CMS) or wiki software with, initially, very little content. Contributors to these systems, who may be paid staff, members of a club or other organisation or members of the public, fill underlying databases with content using editing pages designed for that purpose, while casual visitors view and read this content in its final HTML form. There may or may not be editorial, approval and security systems built into the process of taking newly entered content and making it available to the target visitors.

Remote access

The Internet allows computer users to connect to other computers and information stores easily, wherever they may be across the world. They may do this with or without the use of security, authentication and encryption technologies, depending on the requirements.

This is encouraging new ways of working from home, collaboration and information sharing in many industries. An accountant sitting at home can audit the books of a company based in another country, on a server situated in a third country that is remotely maintained by IT specialists in a fourth. These accounts could have been created by home-working bookkeepers, in other remote locations, based on information e-mailed to them from offices all over the world. Some of these things were possible before the widespread use of the Internet, but the cost of private leased lines would have made many of them infeasible in practice.

An office worker away from his desk, perhaps on the other side of the world on a business trip or a holiday, can open a remote desktop session into his normal office PC using a secure Virtual Private Network (VPN) connection via the Internet. This gives the worker complete access to all of his or her normal files and data, including e-mail and other applications, while away from the office.

This concept is also referred to by some network security people as the Virtual Private Nightmare, because it extends the secure perimeter of a corporate network into its employees' homes; this has been the source of some notable security breaches, but also provides security for the workers.

Collaboration

The low cost and nearly instantaneous sharing of ideas, knowledge, and skills has made collaborative work dramatically easier. Not only can a group cheaply communicate and test, but the wide reach of the Internet allows such groups to easily form in the first place, even among niche interests. An example of this is the free software movement in software development, which produced GNU and Linux from scratch and has taken over development of Mozilla and OpenOffice.org (formerly known as Netscape Communicator and StarOffice).

Internet "chat", whether in the form of IRC "chat rooms" or channels, or via instant messaging systems, allow colleagues to stay in touch in a very convenient way when working at their computers during the day. Messages can be sent and viewed even more quickly and conveniently than via e-mail. Extension to these systems may allow files to be exchanged, "whiteboard" drawings to be shared as well as voice and video contact between team members.

Version control systems allow collaborating teams to work on shared sets of documents without either accidentally overwriting each other's work or having members wait until they get "sent" documents to be able to add their thoughts and changes.

File sharing

A computer file can be e-mailed to customers, colleagues and friends as an attachment. It can be uploaded to a website or FTP server for easy download by others. It can be put into a "shared location" or onto a file server for instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks.

In any of these cases, access to the file may be controlled by user authentication; the transit of the file over the Internet may be obscured by encryption, and money may change hands before or after access to the file is given. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—hopefully fully encrypted—across the Internet. The origin and authenticity of the file received may be checked by digital signatures or by MD5 or other message digests.

These simple features of the Internet, over a worldwide basis, are changing the basis for the production, sale, and distribution of anything that can be reduced to a computer file for transmission. This includes all manner of print publications, software products, news, music, film, video, photography, graphics and the other arts. This in turn has caused seismic shifts in each of the existing industries that previously controlled the production and distribution of these products.

Internet collaboration technology enables business and project teams to share documents, calendars and other information. Such collaboration occurs in a wide variety of areas including scientific research, software development, conference planning, political activism and creative writing.

Streaming media

Many existing radio and television broadcasters provide Internet "feeds" of their live audio and video streams (for example, the BBC). They may also allow time-shift viewing or listening such as Preview, Classic Clips and Listen Again features. These providers have been joined by a range of pure Internet "broadcasters" who never had on-air licenses. This means that an Internet-connected device, such as a computer or something more specific, can be used to access on-line media in much the same way as was previously possible only with a television or radio receiver. The range of material is much wider, from pornography to highly specialized, technical webcasts. Podcasting is a variation on this theme, where—usually audio—material is first downloaded in full and then may be played back on a computer or shifted to a digital audio player to be listened to on the move. These techniques using simple equipment allow anybody, with little censorship or licensing control, to broadcast audio-visual material on a worldwide basis.

Webcams can be seen as an even lower-budget extension of this phenomenon. While some webcams can give full-frame-rate video, the picture is usually either small or updates slowly. Internet users can watch animals around an African waterhole, ships in the Panama Canal, the traffic at a local roundabout or their own premises, live and in real time. Video chat rooms, video conferencing, and remote controllable webcams are also popular. Many uses can be found for personal webcams in and around the home, with and without two-way sound.

YouTube, sometimes described as an Internet phenomenon because of the vast amount of users and how rapidly the site's popularity has grown, was founded on February 15, 2005. It is now the leading website for free streaming video. It uses a flash-based web player which streams video files in the format FLV. Users are able to watch videos without signing up; however, if users do sign up they are able to upload an unlimited amount of videos and they are given their own personal profile. It is currently estimated that there are 64,000,000 videos on YouTube, and it is also currently estimated that 825,000 new videos are uploaded every day.

Voice telephony (VoIP)

VoIP stands for Voice over IP, where IP refers to the Internet Protocol that underlies all Internet communication. This phenomenon began as an optional two-way voice extension to some of the instant messaging systems that took off around the year 2000. In recent years many VoIP systems have become as easy to use and as convenient as a normal telephone. The benefit is that, as the Internet carries the actual voice traffic, VoIP can be free or cost much less than a normal telephone call, especially over long distances and especially for those with always-on Internet connections such as cable or ADSL.

Thus, VoIP is maturing into a viable alternative to traditional telephones. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple, inexpensive VoIP modems are now available that eliminate the need for a PC.

Voice quality can still vary from call to call but is often equal to and can even exceed that of traditional calls.

Remaining problems for VoIP include emergency telephone number dialing and reliability. Currently, a few VoIP providers provide an emergency service, but it is not universally available. Traditional phones are line-powered and operate during a power failure; VoIP does not do so without a backup power source for the electronics.

Most VoIP providers offer unlimited national calling, but the direction in VoIP is clearly toward global coverage with unlimited minutes for a low monthly fee.

VoIP has also become increasingly popular within the gaming world, as a form of communication between players. Popular gaming VoIP clients include Ventrilo and Teamspeak, and there are others available also. The PlayStation 3 and Xbox 360 also offer VoIP chat features.

Internet by region

Internet access

Wikibooks has a book on the topic of

Online linux connect

Common methods of home access include dial-up, landline broadband (over coaxial cable, fiber optic or copper wires), Wi-Fi, satellite and 3G technology cell phones.

Public places to use the Internet include libraries and Internet cafes, where computers with Internet connections are available. There are also Internet access points in many public places such as airport halls and coffee shops, in some cases just for brief use while standing. Various terms are used, such as "public Internet kiosk", "public access terminal", and "Web payphone". Many hotels now also have public terminals, though these are usually fee-based. These terminals are widely accessed for various usage like ticket booking, bank deposit, online payment etc. Wi-Fi provides wireless access to computer networks, and therefore can do so to the Internet itself. Hotspots providing such access include Wi-Fi cafes, where would-be users need to bring their own wireless-enabled devices such as a laptop or PDA. These services may be free to all, free to customers only, or fee-based. A hotspot need not be limited to a confined location. A whole campus or park, or even an entire city can be enabled. Grassroots efforts have led to wireless community networks. Commercial Wi-Fi services covering large city areas are in place in London, Vienna, Toronto, San Francisco, Philadelphia, Chicago and Pittsburgh. The Internet can then be accessed from such places as a park bench.^[8]

Apart from Wi-Fi, there have been experiments with proprietary mobile wireless networks like Ricochet, various high-speed data services over cellular phone networks, and fixed wireless services.

High-end mobile phones such as smartphones generally come with Internet access through the phone network. Web browsers such as Opera are available on these advanced handsets, which can also run a wide variety of other Internet software. More mobile phones have Internet access than PCs, though this is not as widely used. An Internet access provider and protocol matrix differentiates the methods used to get online.

Social impact

The Internet has made possible entirely new forms of social interaction, activities and organizing, thanks to its basic features such as widespread usability and access.

Social networking websites such as Facebook and MySpace have created a new form of socialization and interaction. Users of these sites are able to add a wide variety of items to their personal pages, to indicate common interests, and to connect with others. It is also possible to find a large circle of existing acquaintances, especially if a site allows users to utilize their real names, and to allow communication among large existing groups of people.

Sites like meetup.com exist to allow wider announcement of groups which may exist mainly for face-to-face meetings, but which may have a variety of minor interactions over their group's site at meetup.org, or other similar sites.

Political organization and censorship

In democratic societies, the Internet has achieved new relevance as a political tool. The presidential campaign of Howard Dean in 2004 in the United States became famous for its ability to generate donations via the Internet. Many political groups use the Internet to achieve a whole new method of organizing, in order to carry out Internet activism.

Some governments, such as those of Cuba, Iran, North Korea, Myanmar, the People's Republic of China, and Saudi Arabia, restrict what people in their countries can access on the Internet, especially political and religious content. This is accomplished through software that filters domains and content so that they may not be easily accessed or obtained without elaborate circumvention.

In Norway, Denmark, Finland^[9] and Sweden, major Internet service providers have voluntarily (possibly to avoid such an arrangement being turned into law) agreed to restrict access to sites listed by police. While this list of forbidden URLs is only supposed to contain addresses of known child pornography sites, the content of the list is secret.

Many countries, including the United States, have enacted laws making the possession or distribution of certain material, such as child pornography, illegal, but do not use filtering software.

There are many free and commercially available software programs with which a user can choose to block offensive websites on individual computers or networks, such as to limit a child's access to pornography or violence. See Content-control software.

Leisure activities

The Internet has been a major source of leisure since before the World Wide Web, with entertaining social experiments such as MUDs and MOOs being conducted on university servers, and humor-related Usenet groups receiving much of the main traffic. Today, many Internet forums have sections devoted to games and funny videos; short cartoons in the form of Flash movies are also popular. Over 6 million people use blogs or message boards as a means of communication and for the sharing of ideas.

The pornography and gambling industries have both taken full advantage of the World Wide Web, and often provide a significant source of advertising revenue for other websites. Although many governments have attempted to put restrictions on both industries' use of the Internet, this has generally failed to stop their widespread popularity.

One main area of leisure on the Internet is multiplayer gaming. This form of leisure creates communities, bringing people of all ages and origins to enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing games to online gambling. This has revolutionized the way many people interact and spend their free time on the Internet.

While online gaming has been around since the 1970s, modern modes of online gaming began with services such as GameSpy and MPlayer, to which players of games would typically subscribe. Non-subscribers were limited to certain types of gameplay or certain games.

Many use the Internet to access and download music, movies and other works for their enjoyment and relaxation. As discussed above, there are paid and unpaid sources for all of these, using centralized servers and distributed peer-to-peer technologies. Discretion is needed as some of these sources take more care over the original artists' rights and over copyright laws than others.

Many use the World Wide Web to access news, weather and sports reports, to plan and book holidays and to find out more about their random ideas and casual interests.

People use chat, messaging and e-mail to make and stay in touch with friends worldwide, sometimes in the same way as some previously had pen pals. Social networking websites like MySpace, Facebook and many others like them also put and keep people in contact for their enjoyment.

The Internet has seen a growing number of Web desktops, where users can access their files, folders, and settings via the Internet.

Cyberslacking has become a serious drain on corporate resources; the average UK employee spends 57 minutes a day surfing the Web at work, according to a study by Peninsula Business Services.^[10]

Complex architecture

Many computer scientists see the Internet as a "prime example of a large-scale, highly engineered, yet highly complex system".^[11] The Internet is extremely heterogeneous. (For instance, data transfer rates and physical characteristics of connections vary widely.) The Internet exhibits "emergent phenomena" that depend on its large-scale organization. For example, data transfer rates exhibit temporal self-similarity. Further adding to the complexity of the Internet is the ability of more than one computer to use the Internet through only one node, thus creating the possibility for a very deep and hierarchal sub-network that can theoretically be extended infinitely (disregarding the programmatic limitations of the IPv4 protocol). However, since principles of this architecture date back to the 1960s, it might not be a solution best suited to modern needs, and thus the possibility of developing alternative structures is currently being looked into.^[12]

According to a June 2007 article in Discover magazine, the combined weight of all the electrons moved within the Internet in a day is 0.2 millionths of an ounce.^[13] Others have estimated this at nearer 2 ounces (50 grams).^[14]

Marketing

The Internet has also become a large market for companies; some of the biggest companies today have grown by taking advantage of the efficient nature of low-cost advertising and commerce through the Internet, also known as e-commerce. It is the fastest way to spread information to a vast number of people simultaneously. The Internet has also subsequently revolutionized shopping—for example; a person can order a CD online and receive it in the mail within a couple of days, or download it directly in some cases. The Internet has also greatly facilitated personalized marketing which allows a company to market a product to a specific person or a specific group of people more so than any other advertising medium.

Examples of personalized marketing include online communities such as MySpace, Friendster, Orkut, Facebook and others which thousands of Internet users join to advertise themselves and make friends online. Many of these users are young teens and adolescents ranging from 13 to 25 years old. In turn, when they advertise themselves they advertise interests and hobbies, which online marketing companies can use as information as to what those users will purchase online, and advertise their own companies' products to those users.

Further information: Disintermediation#Impact of Internet-related disintermediation upon various industries and Travel agency#The Internet threat

The terms “internet” and “Internet”

Look up Internet, internet in Wiktionary, the free dictionary.

The term internet is written both with capital and without capital, and is used both with and without article. This can be explained from the various ways in which the term has come to be used over time.

The term originated as a determiner, a shorthand for internetworking, and is mostly used in this way in RFCs, the documentation for the evolving Internet Protocol (IP) standards for internetworking between ARPANET and other computer networks in the 1970s. As the impetus behind IP grew, it became more common to regard the results of internetworking as entities of their own, and internet became a noun, used both in a generic sense (any collection of computer networks connected through internetworking) and in a specific sense (the collection of computer networks that internetworked with ARPANET, and later NSFNET, using the IP standards, and that grew into the connectivity service we know today).

In its generic sense, internet is a common noun, a synonym for internetwork; therefore, it has a plural form (first appearing in RFC 870 and RFC 872),^{[citation needed]} and is not to be capitalized.

In its specific sense, it is a proper noun, and therefore, with article, without a plural form, and with capitalization.^[15]

A sentence that uses both meanings:

 The Internet is an internet based on the Internet Protocol suite.

The proper noun can again be used as a determiner, which will then carry a capital (e.g. "Internet mail").

The Internet Society, the Internet Engineering Task Force (IETF), the Internet Corporation for Assigned Names and Numbers (ICANN), the World Wide Web Consortium (W3C), and several other Internet-related organizations use this convention in their publications, including the RFCs.

As Internet connectivity grew more popular, it became known as a service, similar to TV, radio, and telephone, and the word came to be used in this way (e.g. "I have Internet at home" and "I saw it on (the) Internet"). For this type of use, English spelling and grammar do not prescribe whether the article or capitalization are to be used, which explains the inconsistency that exists in practice.

Many newspapers, newswires, periodicals, and technical journals capitalize the term (Internet). Examples include The Dhaka Daily Star, The New York Times, the Associated Press, Time, The Times of India, Hindustan Times, and Communications of the ACM.

Other publications do not capitalize the term, including The Economist, the Canadian Broadcasting Corporation, the Financial Times, The Guardian, The Times, and The Sydney Morning Herald Wired News; this appears to be more popular outside North America.

Network Routers

noreply@blogger.com (Beauty Schools) — Sat, 02 Aug 2008 09:10:00 +0000

from www.networkliquidators.com

Network Liquidators is your premier online destination for buying and selling routers. We keep an extensive inventory of network routers in stock at most times which are usually available for overnight delivery. Along with our used routers, we also carry many other networking products including memory, gbics, interface cards, network modules, switches, cables, gbics, chassis, and various other parts and accessories.

All of our network routers go through a grueling inspection, testing, and refurbishing process and all of our networking routers comes standard with our Lifetime Warranty (end-user customers only). For details about our inspection, testing, and refurbishing process, click here.

If you cannot find the refurbished routers you are looking for, please call one of our account executives at 1-800-998-9862 for a custom quote. If you are not sure which network router you need, we have technicians on staff experienced with networking products that can help you with your configurations.

We both buy and sell new, used and refurbished network routers and other networking accessories. Let us know if you have any surplus of routers that you are looking to sell and we will immediately reply with fair market value. Please call our purchasing department at 1-800-998-9862. Below is a listing of some of our more popular routers. If you are looking to buy routers at a great price, then Network Liquidators is for you.

Computer

noreply@blogger.com (Beauty Schools) — Sat, 02 Aug 2008 08:58:00 +0000

From Wikipedia, the free encyclopedia

The NASA Columbia Supercomputer

A computer is a machine that manipulates data according to a list of instructions.

The first devices that resemble modern computers date to the mid-20th century (around 1940 - 1945), although the computer concept and various machines similar to computers existed earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers.^[1] Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space.^[2] Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as "a computer"; however, the most common form of computer in use today is the embedded computer. Embedded computers are small, simple devices that are used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and children's toys.

The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.

History of computing

The Jacquard loom was one of the first programmable devices.

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.

The history of the modern computer begins with two separate technologies - that of automated calculation and that of programmability.

Examples of early mechanical calculating devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers. However, none of those devices fit the modern definition of a computer because they could not be programmed.

Hero of Alexandria (c. 10 – 70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions - and when.^[3] This is the essence of programmability. In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.

It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine".^[4] Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.

Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.

During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.

*Defining characteristics of some early digital computers of the 1940s* (In the history of computing hardware)
Name	First operational	Numeral system	Computing mechanism	Programming	Turing complete
Zuse Z3 (Germany)	May 1941	Binary	Electro-mechanical	Program-controlled by punched film stock	Yes (1998)
Atanasoff–Berry Computer (US)	Summer 1941	Binary	Electronic	Not programmable—single purpose	No
Colossus (UK)	January 1944	Binary	Electronic	Program-controlled by patch cables and switches	No
Harvard Mark I – IBM ASCC (US)	1944	Decimal	Electro-mechanical	Program-controlled by 24-channel punched paper tape (but no conditional branch)	Yes (1998)
ENIAC (US)	November 1945	Decimal	Electronic	Program-controlled by patch cables and switches	Yes
Manchester Small-Scale Experimental Machine (UK)	June 1948	Binary	Electronic	Stored-program in Williams cathode ray tube memory	Yes
Modified ENIAC (US)	September 1948	Decimal	Electronic	Program-controlled by patch cables and switches plus a primitive read-only stored programming mechanism using the Function Tables as program ROM	Yes
EDSAC (UK)	May 1949	Binary	Electronic	Stored-program in mercury delay line memory	Yes
Manchester Mark I (UK)	October 1949	Binary	Electronic	Stored-program in Williams cathode ray tube memory and magnetic drum memory	Yes
CSIRAC (Australia)	November 1949	Binary	Electronic	Stored-program in mercury delay line memory	Yes

A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult (Shannon 1940). Notable achievements include:

EDSAC was one of the first computers to implement the stored program (von Neumann) architecture.

Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.
The non-programmable Atanasoff–Berry Computer (1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory.
The secret British Colossus computers (1943)^[5], which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.
The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.
The U.S. Army's Ballistics Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.

Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the "stored program architecture" or von Neumann architecture. This design was first formally described by John von Neumann in the paper First Draft of a Report on the EDVAC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture commenced around this time, the first of these being completed in Great Britain. The first to be demonstrated working was the Manchester Small-Scale Experimental Machine (SSEM or "Baby"), while the EDSAC, completed a year after SSEM, was the first practical implementation of the stored program design. Shortly thereafter, the machine originally described by von Neumann's paper—EDVAC—was completed but did not see full-time use for an additional two years.

Nearly all modern computers implement some form of the stored-program architecture, making it the single trait by which the word "computer" is now defined. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture.

Microprocessors are miniaturized devices that often implement stored program CPUs.

Computers that used vacuum tubess as their electronic elements were in use throughout the 1950s. Vacuum tube electronics were largely replaced in the 1960s by transistor-based electronics, which are smaller, faster, cheaper to produce, require less power, and are more reliable. In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. By the 1980s, computers became sufficiently small and cheap to replace simple mechanical controls in domestic appliances such as washing machines. The 1980s also witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household.

Stored program architecture

The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that a list of instructions (the program) can be given to the computer and it will store them and carry them out at some time in the future.

In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to the instruction following that jump instruction.

Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention.

Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time—with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. For example:

        mov      #0,sum     ; set sum to 0
       mov      #1,num     ; set num to 1
loop:   add      num,sum    ; add num to sum
       add      #1,num     ; add 1 to num
       cmp      num,#1000  ; compare num to 1000
       ble      loop       ; if num <= 1000, go back to 'loop'
       halt                ; end of program. stop running

Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in about a millionth of a second.

However, computers cannot "think" for themselves in the sense that they only solve problems in exactly the way they are programmed to. An intelligent human faced with the above addition task might soon realize that instead of actually adding up all the numbers one can simply use the equation

and arrive at the correct answer (500,500) with little work. In other words, a computer programmed to add up the numbers one by one as in the example above would do exactly that without regard to efficiency or alternative solutions.

Programs

A 1970s punched card containing one line from a FORTRAN program. The card reads: "Z(1) = Y + W(1)" and is labelled "PROJ039" for identification purposes.

In practical terms, a computer program may run from just a few instructions to many millions of instructions, as in a program for a word processor or a web browser. A typical modern computer can execute billions of instructions per second (gigahertz or GHz) and rarely make a mistake over many years of operation. Large computer programs comprising several million instructions may take teams of programmers years to write, thus the probability of the entire program having been written without error is highly unlikely.

Errors in computer programs are called "bugs". Bugs may be benign and not affect the usefulness of the program, or have only subtle effects. But in some cases they may cause the program to "hang" - become unresponsive to input such as mouse clicks or keystrokes, or to completely fail or "crash". Otherwise benign bugs may sometimes may be harnessed for malicious intent by an unscrupulous user writing an "exploit" - code designed to take advantage of a bug and disrupt a program's proper execution. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.

In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode, the command to multiply them would have a different opcode and so on. The simplest computers are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from—each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer just as if they were numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches.

While it is possible to write computer programs as long lists of numbers (machine language) and this technique was used with many early computers, it is extremely tedious to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember—a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler. Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. For instance, an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.

Though considerably easier than in machine language, writing long programs in assembly language is often difficult and error prone. Therefore, most complicated programs are written in more abstract high-level programming languages that are able to express the needs of the computer programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler.^[11] Since high level languages are more abstract than assembly language, it is possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles.

The task of developing large software systems is an immense intellectual effort. Producing software with an acceptably high reliability on a predictable schedule and budget has proved historically to be a great challenge; the academic and professional discipline of software engineering concentrates specifically on this problem.

Example

A traffic light showing red.

Suppose a computer is being employed to drive a traffic light. A simple stored program might say:

Turn off all of the lights
Turn on the red light
Wait for sixty seconds
Turn off the red light
Turn on the green light
Wait for sixty seconds
Turn off the green light
Turn on the yellow light
Wait for two seconds
Turn off the yellow light
Jump to instruction number (2)

With this set of instructions, the computer would cycle the light continually through red, green, yellow and back to red again until told to stop running the program.

However, suppose there is a simple on/off switch connected to the computer that is intended to be used to make the light flash red while some maintenance operation is being performed. The program might then instruct the computer to:

Turn off all of the lights
Turn on the red light
Wait for sixty seconds
Turn off the red light
Turn on the green light
Wait for sixty seconds
Turn off the green light
Turn on the yellow light
Wait for two seconds
Turn off the yellow light
If the maintenance switch is NOT turned on then jump to instruction number 2
Turn on the red light
Wait for one second
Turn off the red light
Wait for one second
Jump to instruction number 11

In this manner, the computer is either running the instructions from number (2) to (11) over and over or its running the instructions from (11) down to (16) over and over, depending on the position of the switch.

How computers work

A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires.

The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

Control unit

The control unit (often called a control system or central controller) directs the various components of a computer. It reads and interprets (decodes) instructions in the program one by one. The control system decodes each instruction and turns it into a series of control signals that operate the other parts of the computer.^[13] Control systems in advanced computers may change the order of some instructions so as to improve performance.

A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.^[14]

Diagram showing how a particular MIPS architecture instruction would be decoded by the control system.

The control system's function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:

Read the code for the next instruction from the cell indicated by the program counter.
Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.
Provide the necessary data to an ALU or register.
If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
Write the result from the ALU back to a memory location or to a register or perhaps an output device.
Jump back to step (1).

Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).

It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program - and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen.

Arithmetic/logic unit (ALU)

The ALU is capable of performing two classes of operations: arithmetic and logic.

The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?").

Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic.

Superscalar computers contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.

Memory

Magnetic core memory was popular main memory for computers through the 1960s until it was completely replaced by semiconductor memory.

A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is up to the software to give significance to what the memory sees as nothing but a series of numbers.

In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers; either from 0 to 255 or -128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory as long as it can be somehow represented in numerical form. Modern computers have billions or even trillions of bytes of memory.

The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. Since data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed.

Computer main memory comes in two principal varieties: random access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM is erased when the power to the computer is turned off while ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the software required to perform the task may be stored in ROM. Software that is stored in ROM is often called firmware because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM by retaining data when turned off but being rewritable like RAM. However, flash memory is typically much slower than conventional ROM and RAM so its use is restricted to applications where high speeds are not required.^[15]

In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

Input/output (I/O)

Hard disks are common I/O devices used with computers.

I/O is the means by which a computer receives information from the outside world and sends results back. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.

Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics^{[citation needed]}. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.

Multitasking

While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time", then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn.

Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.

Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly - in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.

Multiprocessing

Cray designed many supercomputers that used multiprocessing heavily.

Some computers may divide their work between one or more separate CPUs, creating a multiprocessing configuration. Traditionally, this technique was utilized only in large and powerful computers such as supercomputers, mainframe computers and servers. However, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers have become widely available and are beginning to see increased usage in lower-end markets as a result.

Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers.^[16] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks.

Networking and the Internet

Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.

In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

Further topics

Hardware

The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware.

**History of computing hardware**
First Generation (Mechanical/Electromechanical)	Calculators	Antikythera mechanism, Difference Engine, Norden bombsight
First Generation (Mechanical/Electromechanical)	Programmable Devices	Jacquard loom, Analytical Engine, Harvard Mark I, Z3
Second Generation (Vacuum Tubes)	Calculators	Atanasoff–Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120
Second Generation (Vacuum Tubes)	Programmable Devices	Colossus, ENIAC, Manchester Small-Scale Experimental Machine, EDSAC, Manchester Mark I, CSIRAC, EDVAC, UNIVAC I, IBM 701, IBM 702, IBM 650, Z22
Third Generation (Discrete transistors and SSI, MSI, LSI Integrated circuits)	Mainframes	IBM 7090, IBM 7080, System/360, BUNCH
	Minicomputer	PDP-8, PDP-11, System/32, System/36
Fourth Generation (VLSI integrated circuits)	Minicomputer	VAX, IBM System i
	4-bit microcomputer	Intel 4004, Intel 4040
	8-bit microcomputer	Intel 8008, Intel 8080, Motorola 6800, Motorola 6809, MOS Technology 6502, Zilog Z80
	16-bit microcomputer	Intel 8088, Zilog Z8000, WDC 65816/65802
	32-bit microcomputer	Intel 80386, Pentium, Motorola 68000, ARM architecture
	64-bit microcomputer^[17]	x86-64, PowerPC, MIPS, SPARC
	Embedded computer	Intel 8048, Intel 8051
	Personal computer	Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet computer, Wearable computer
Theoretical/experimental	Quantum computer, Chemical computer, DNA computing, Optical computer, Spintronics based computer

**Other Hardware Topics**
Peripheral device (Input/output)	Input	Mouse, Keyboard, Joystick, Image scanner
	Output	Monitor, Printer
	Both	Floppy disk drive, Hard disk, Optical disc drive, Teleprinter
Computer busses	Short range	RS-232, SCSI, PCI, USB
Computer busses	Long range (Computer networking)	Ethernet, ATM, FDDI

Software

Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware" to indicate that it falls into an uncertain area somewhere between hardware and software.

**Computer software**
Operating system	Unix/BSD	UNIX System V, AIX, HP-UX, Solaris (SunOS), IRIX, List of BSD operating systems
	GNU/Linux	List of Linux distributions, Comparison of Linux distributions
	Microsoft Windows	Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Vista, Windows CE
	DOS	86-DOS (QDOS), PC-DOS, MS-DOS, FreeDOS
	Mac OS	Mac OS classic, Mac OS X
	Embedded and real-time	List of embedded operating systems
	Experimental	Amoeba, Oberon/Bluebottle, Plan 9 from Bell Labs
Library	Multimedia	DirectX, OpenGL, OpenAL
Library	Programming library	C standard library, Standard template library
Data	Protocol	TCP/IP, Kermit, FTP, HTTP, SMTP
Data	File format	HTML, XML, JPEG, MPEG, PNG
User interface	Graphical user interface (WIMP)	Microsoft Windows, GNOME, KDE, QNX Photon, CDE, GEM
User interface	Text user interface	Command line interface, shells
Application	Office suite	Word processing, Desktop publishing, Presentation program, Database management system, Scheduling & Time management, Spreadsheet, Accounting software
	Internet Access	Browser, E-mail client, Web server, Mail transfer agent, Instant messaging
	Design and manufacturing	Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
	Graphics	Raster graphics editor, Vector graphics editor, 3D modeler, Animation editor, 3D computer graphics, Video editing, Image processing
	Audio	Digital audio editor, Audio playback, Mixing, Audio synthesis, Computer music
	Software Engineering	Compiler, Assembler, Interpreter, Debugger, Text Editor, Integrated development environment, Performance analysis, Revision control, Software configuration management
	Educational	Edutainment, Educational game, Serious game, Flight simulator
	Games	Strategy, Arcade, Puzzle, Simulation, First-person shooter, Platform, Massively multiplayer, Interactive fiction
	Misc	Artificial intelligence, Antivirus software, Malware scanner, Installer/Package management systems, File manager

Programming languages

Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine language by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques. There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications.

**Programming Languages**
Lists of programming languages	Timeline of programming languages, Categorical list of programming languages, Generational list of programming languages, Alphabetical list of programming languages, Non-English-based programming languages
Commonly used Assembly languages	ARM, MIPS, x86
Commonly used High level languages	BASIC, C, C++, C#, COBOL, Fortran, Java, Lisp, Pascal
Commonly used Scripting languages	Bourne script, JavaScript, Python, Ruby, PHP, Perl

Professions and organizations

As the use of computers has spread throughout society, there are an increasing number of careers involving computers. Following the theme of hardware, software and firmware, the brains of people who work in the industry are sometimes known irreverently as wetware or "meatware".

**Computer-related professions**
Hardware-related	Electrical engineering, Electronics engineering, Computer engineering, Telecommunications engineering, Optical engineering, Nanoscale engineering
Software-related	Computer science, Human-computer interaction, Information technology, Software engineering, Scientific computing, Web design, Desktop publishing

The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature.

**Organizations**
Standards groups	ANSI, IEC, IEEE, IETF, ISO, W3C
Professional Societies	ACM, ACM Special Interest Groups, IET, IFIP
Free/Open source software groups	Free Software Foundation, Mozilla Foundation, Apache Software Foundation