The Internet is the worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of the World Wide Web.
Contrary to some common usage, the Internet and the World Wide Web are not synonymous: the Internet is a collection of interconnected computer networks, linked by copper wires, fiber-optic cables, wireless connections etc.; the Web is a collection of interconnected documents, linked by hyperlinks and URLs. The World Wide Web is accessible via the Internet, along with many other services including e-mail, file sharing and others described below.
Creation of the Internet
Main article: History of the Internet
The USSR's launch of Sputnik spurred the United States to create the Advanced Research Projects Agency (ARPA, later known as the Defense Advanced Research Projects Agency, or DARPA) in February 1958 to regain a technological lead. ARPA created the Information Processing Technology Office (IPTO) to further the research of the Semi Automatic Ground Environment 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 recruited Lawrence Roberts to head a project to implement a network, and Roberts based the technology on the work of Paul Baran 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 node went live at UCLA on October 29, 1969 on what would be called the ARPANET, the "eve" network of today's Internet.
The first TCP/IP wide area network was operational by 1 January 1983, when the United States' National Science Foundation (NSF) constructed a university network backbone that would later become the NSFNet. (This date is held by some to be technically that of the birth of the Internet.) It was then followed by the opening of the network to commercial interests in 1985. Important separate networks that offered gateways into, then later merged into the NSFNet include Usenet, Bitnet and the various commercial and educational X.25 Compuserve and JANET. Telenet (later called Sprintnet), was a large privately-funded national computer network with free dialup access in cities throughout the U.S. that had been in operation since the 1970s. This network eventually merged with the others in the 1990s as the TCP/IP protocol became increasingly popular. The ability of TCP/IP to work over these pre-existing communication networks allowed for a great ease of growth. Use of Internet as a phrase to describe a single global TCP/IP network originated around this time.
The network gained a public face in the 1990s. In August 1991 CERN, which straddles the border between France and Switzerland publicized the new World Wide Web project, two years after Tim Berners-Lee had begun creating HTML, HTTP and the first few web pages at CERN.
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 at Urbana-Champaign released version 1.0 of Mosaic and by late 1994 there was growing public interest in the previously academic/technical Internet. By 1996 the word "Internet" was common public currency, but it referred almost entirely 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). 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.
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Today's Internet
Aside from the complex physical connections that make up its infrastructure, the Internet is held together by bi- or multi-lateral commercial contracts (for example peering agreements) and by technical specifications or protocols that describe how to exchange data over the network. Indeed, the Internet is essentially defined by its interconnections and routing policies.
As of March 31st, 2006, over 1.02 billion people use the Internet according to Internet World Stats.
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Internet protocols
In this context, there are three layers of protocols:
At the lowest level is IP, which defines the datagrams or packets that carry blocks of data from one node to another. The vast majority of today's Internet uses version four of the IP protocol (i.e. IPv4), and although IPv6 is standardised, it exists only as "islands" of connectivity, and there are many ISPs who don't have any IPv6 connectivity at all.[1]
Next comes TCP and UDP - the protocols by which one host sends data to another. The former makes a virtual 'connection', which gives some level of guarantee of reliability. The latter is a best-effort, connection-less transport, in which data packets that are lost in transit will not be re-sent.
On top comes the application protocol. This defines the specific messages and data formats sent and understood by the applications running at each end of the communication.
Unlike older communications systems, the Internet protocol suite was deliberately designed to be independent of the underlying physical medium. Any communications network, wired or wireless, that can carry two-way digital data can carry Internet traffic. Thus, Internet packets flow through wired networks like copper wire, coaxial cable, and fibre optic, and through wireless networks like Wi-Fi. Together, all these networks, sharing the same protocols, form the Internet.
The Internet protocols originate from discussions within the Internet Engineering Task Force (IETF) and its working groups, which are open to public participation and review. These committees produce documents that are known as Request for Comments documents (RFCs). Some RFCs are raised to the status of Internet Standard by the IETF process.
Some of the most-used application protocols in the Internet protocol suite are DNS, POP3, IMAP, SMTP, HTTP, HTTPS and FTP. There are many other important ones; see the lists provided in these articles.
All services on the Internet make use of defined application protocols. Of these, e-mail and the World Wide Web are among the most well known, and other services are built upon these, such as mailing lists and blogs. There are many others that are necessary 'behind the scenes' and yet others that serve specialised requirements.
Some application protocols were not created out of the IETF process, but initially as part of proprietary commercial or private experimental systems. They became much more widely used and have now become de facto or actual standards in their own right. Examples of these include IRC chat rooms, and various instant messaging and peer-to-peer file sharing protocols.
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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 how the commercial Internet providers connect via Internet exchange points, research networks tend to interconnect into large subnetworks such as:
GEANT
GLORIAD
Internet2
JANET (the UK's Joint Academic Network aka UKERNA)
These in turn are built around relatively smaller networks. See also the list of academic computer network organizations
In network schematic diagrams, the Internet is often represented by a cloud symbol, into and out of which network communications can pass.
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ICANN
Main article: ICANN
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 addresses, and protocol port and parameter numbers. A globally unified namespace (i.e., a system of names in which there is one and only one holder of each 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, as such, 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, Internet protocol addresses, and protocol port and parameter numbers.
On Nov. 16, 2005, the World Summit on the Information Society, held in Tunis, established the Internet Governance Forum (IGF) to discuss Internet-related issues
The World Wide Web
Main article: World Wide Web
Through keyword-driven Internet research using search engines like Google, millions 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.
Many individuals and some companies and groups have adopted the use of 'weblogs' or blogs, which are largely used as easily-updatable online diaries. Some commercial organizations 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.
For more information on the distinction between the World Wide Web and the Internet itself — as in everyday use the two are sometimes confused — see Dark internet where this is discussed in more detail.
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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 book-keepers, 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 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 him complete access to all his normal files and data, including e-mail and other applications, while he is away.
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.
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Collaboration
See also: Collaborative software
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/Libre/Open-Source Software (FLOSS) movement in software development, such as Linux, Mozilla, and OpenOffice.org. Cooperation has been greatly eased in other fields, as well.
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File-sharing
Main article: 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, such as BitTorrent 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 world-wide 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 office documents, publications, software products, music, photography, video, animations, graphics and the other arts. This in turn is causing seismic shifts in each of the existing industry associations, such as the RIAA and MPAA in the United States, that previously controlled the production and distribution of these products in that country.
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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 licences. 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 TV or radio receiver. The range of material is much wider, from pornography to highly specialised technical web-casts. 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.
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VoIP
Main article: 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 ADSL or DSL Internet connections.
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 some 911 dialing 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.
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Language
Main article: English on the Internet
The most 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 the lingua franca. It may also be related to the poor capability of early computers to handle characters other than those in the basic Latin alphabet.
Further information: Unicode
After English (32% of web visitors) the most-requested languages on the world wide web are Chinese 13%, Japanese 8%, Spanish 7%, German 6% and French 4% (from Internet World Stats, updated November 30, 2005).
By continent, 34% of the world's Internet users are based in Asia, 29% in Europe, and 23% in North America ([2] updated November 21, 2005).
The Internet's technologies have developed enough in recent years that good facilities are available for development and communication in most widely used languages. However, some glitches such as mojibake (also known as krakozyabry) still remain.
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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 has given employees a forum from which to voice their opinions about their jobs, employers and co-workers, creating a massive amount of information and data on work that is currently being collected by the Worklifewizard.org project run by Harvard Law School's Labor & Worklife Program.
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Censorship
Main article: Internet censorship
Some governments, such as in Iran, China and France restrict what people in their countries can access on the Internet, especially political and religious content, through software that filters domains and content, so they may be easily accessed or obtained without elaborate circumvention.
Many countries 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 Web sites on individual computers or networks, such as to limit a child's access to pornography or violence. See Content-control software.
Internet access
Common methods of home access include dial-up, landline broadband (over coaxial cable, fibre optic or copper wires), Wi-Fi, satellite and 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.
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 a would-be user needs 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. The whole campus or park, or even the entire city can be enabled. Grassroots efforts have led to wireless community networks. Commercial WiFi services covering large city areas are in place in London, Vienna, San Francisco, Philadelphia, Chicago, Pittsburgh and other cities, including Toronto by the end of 2006. The Internet can then be accessed from such places as a park bench.[1]
Apart from Wi-Fi, there have been experiments with proprietary mobile wireless networks like Ricochet, various high-speed data services over cellular or mobile phone networks, and fixed wireless services.
High end mobile phones such as Symbian 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.
Leisure
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.
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 Web sites. 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, which players of games would typically subscribe to. 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 centralised 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 email to make and stay in touch with friends worldwide, sometimes in the same way as some previously had pen pals. Social networking web sites like Friends Reunited and many others like them also put and keep people in contact for their enjoyment.
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[3].
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A complex system
Many computer scientists see the Internet as a "prime example of a large-scale, highly engineered, yet highly complex system" (Willinger, et al). 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.
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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 amount 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 moreso than any other advertising medium.
Examples of personalized marketing include online communities such as Myspace, Friendster, 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.
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The name Internet
Main article: Internet capitalization conventions
Internet is traditionally written with a capital first letter, as it is a proper noun. The Internet Society, the Internet Engineering Task Force, the Internet Corporation for Assigned Names and Numbers, the World Wide Web Consortium, and several other Internet-related organizations use this convention in their publications.
Many newspapers, newswires, periodicals, and technical journals capitalize the term. Examples include the New York Times, the Associated Press, Time, The Times of India, Hindustan Times, and Communications of the ACM.
Others assert that the first letter should be written small (internet). A significant number of publications use this form, including The Economist, the Financial Times, The Guardian, The Times, and The Sydney Morning Herald. As of 2005, many publications using internet appear to be located outside of North America—although one U.S. news source, Wired News, has adopted the lower case spelling.
Historically, Internet and internet have had different meanings, with internet being a contraction of internetwork or internetworking and Internet referring to the worldwide network. Under this distinction, the Internet is a particular internet, but the reverse does not apply. The distinction was evident in many RFCs, books, and articles from the 1980s and early 1990s, but has recently fallen into disuse