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The '''Internet''' is a worldwide, publicly accessible series of interconnected [[computer network]]s that transmit [[data (computing)|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 [[e-mail|electronic mail]], [[online chat]], [[computer file|file]] transfer, and the interlinked web pages and other resources of the [[World Wide Web]] (WWW).

==Terminology==
The Internet and the [[World Wide Web]] are not synonymous. The Internet is a collection of interconnected ''[[computer networks]]'', linked by [[copper]] wires, [[optical fiber|fiber-optic]] cables, [[wireless]] connections, etc. In contrast, the Web is a collection of interconnected documents and other ''[[Resource (Web)|resources]]'', linked by [[hyperlink]]s and [[Uniform Resource Locator|URLs]]. The World Wide Web is one of the services accessible via the Internet, along with various others including [[e-mail]], [[file sharing]], [[online gaming]] and others described below.

==History==
{{main|History of the Internet}}

===Creation===
{{main|ARPANET}}   

The [[Soviet Union|USSR]]'s launch of [[Sputnik]] spurred the [[United States]] to create the Advanced Research Projects Agency, known as ARPA, in February [[1958 in science|1958]] to regain a technological lead.<ref>{{cite web | url=http://www.darpa.mil/body/arpa_darpa.html | title=ARPA/DARPA | accessdate=2007-05-21 | publisher=Defense Advanced Research Projects Agency}}</ref><ref>{{cite web | url=http://www.darpa.mil/body/overtheyears.html | title=DARPA Over the Years | accessdate=2007-05-21 | publisher=Defense Advanced Research Projects Agency}}</ref> 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 [[Massachusetts Institute of Technology|MIT]] in [[1950 in science|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 in science|1957]] he became a Vice President at [[BBN Technologies|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 (scientist)|Lawrence Roberts]] to head a project to implement a network, and Roberts based the technology on the work of [[Paul Baran]],{{Fact|date=August 2007}} who had written an exhaustive study for the [[United States Air Force|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 [[University of California, Los Angeles|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 [[General Post Office (United Kingdom)|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 in science|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 674, 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 [[Internet protocol suite|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 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 [[England|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)|Mosaic]] web browser. In 1993, the [[National Center for Supercomputing Applications]] at the [[University of Illinois at Urbana-Champaign|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 misuse as a 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.<ref>{{cite paper | url=http://www.dtc.umn.edu/~odlyzko/doc/internet.size.pdf | title=The size and growth rate of the Internet | accessdate=2007-05-21 | author=Coffman, K. G; [[Odlyzko]], A. M. | publisher=AT&T Labs | date=1998-10-02}}</ref> 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. {{Fact|date=September 2007}}

===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.<ref>[http://www.littletechshoppe.com/ns1625/nshist47.html History of Nova Scotia]</ref> 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==

[[Image:My Opera Server.jpg|thumb|The [[Opera (Internet suite)|Opera]] Community 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 HTTP Server|Apache]] front ends, Apache back ends, slave MySQL database servers, [[load balancer]]s, [[file server]]s, 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 agreement]]s), and by technical specifications or [[communications protocol|protocol]]s that describe how to exchange [[data]] over the network. Indeed, the Internet is essentially defined by its interconnections and routing policies.

As of [[December 30]] [[2007]], 1.319 billion people use the Internet according to [http://www.internetworldstats.com/stats.htm Internet World Stats]. Writing in the ''[[Harvard International Review]]'', philosopher N.J. Slabbert, a writer on policy issues for the [[Washington, D.C.]]–based Urban Land Institute, has asserted that the Internet is fast becoming a basic feature of global civilization, so that what has traditionally been called "[[civil society]]" is now becoming identical with information technology society as defined by Internet use.

===Internet protocols===
{{details|Internet Protocols}}
In this context, there are three layers of protocols:
* At the lower level ([[OSI model|OSI]] layer 3) is '''[[Internet Protocol|IP]]''' (Internet Protocol), which defines the datagrams or [[packet (information technology)|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 standardized, it exists only as "islands" of connectivity, and there are many ISPs without any IPv6 connectivity.<ref>[http://www.livinginternet.com Living Internet]</ref> '''[[Internet Control Message Protocol|ICMP]]''' (Internet Control Message Protocol) also exists at this level. ICMP is connectionless; it is used for control, signaling, and error reporting purposes.

* '''[[Transmission Control Protocol|TCP]]''' (Transmission Control Protocol) and '''[[User Datagram Protocol|UDP]]''' (User Datagram Protocol) exist at the next layer up (OSI layer 4); these are the protocols by which data is transmitted. TCP makes a virtual "connection", which gives some level of guarantee of reliability. UDP is a best-effort, connectionless transport, in which data packets that are lost in transit will not be re-sent.

* The '''[[Application layer|application protocols]]''' sit on top of TCP and UDP and occupy layers 5, 6, and 7 of the OSI model. These define the specific messages and data formats sent and understood by the applications running at each end of the communication.  Examples of these protocols are HTTP, FTP, and SMTP.

===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 network]]s.

Similar to the way the commercial Internet providers connect via [[Internet exchange point]]s, research networks tend to interconnect into large subnetworks such as:

*[[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 [[:Category:Academic computer network organizations|academic computer network organizations]].

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

===ICANN===
[[Image:Icannheadquarters.jpg|thumb|right|ICANN headquarters in [[Marina Del Rey]], [[California]], [[United States]]]]
{{details|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 name]]s, 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 [[DNS root zone|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, [[IP address]]es, 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===
{{details|English on the Internet}}
{{further|[[Unicode]]}}
The prevalent language for communication on the Internet is [[English language|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, largely originating in the [[United States]], to handle characters other than those in the English variant of the [[Latin alphabet]]. 

After English (31% of Web visitors) the most requested languages on the [[World Wide Web]] are [[Chinese language|Chinese]] (16%), [[Spanish language|Spanish]] (9%), [[Japanese language|Japanese]] (7%), [[German language|German]] (5%) and [[French language|French]] (5%).<ref>[http://www.internetworldstats.com/stats7.htm Internet World Stats], updated June 30, 2007</ref>
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By continent, 37% of the world's Internet users are based in [[Asia]], 27% in [[Europe]], 19% in [[North America]], and 9% in [[Latin America]] and the [[Carribean]].<ref>[http://www.internetworldstats.com/stats.htm World Internet Usage Statistics News and Population Stats] updated September 30, 2007</ref>
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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 application]]s.

===The Internet viewed on mobile devices===
The Internet can now be accessed virtually anywhere by numerous means. [[Mobile phone]]s, [[datacard]]s, [[handheld]] [[game console]]s and [[cellular router]]s allow users to connect to the Internet from anywhere there is a cellular network supporting that device's technology.

==Common uses of the Internet==
===E-mail===
{{details|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 [[information technology|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===
{{details|World Wide Web}}
[[Image:WorldWideWebAroundWikipedia.png|thumb|300px|Graphic representation of a minute fraction of the [[World Wide Web|WWW]], demonstrating [[hyperlink]]s]]

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 [[hyperlink]]s and [[Uniform Resource Locator|URL]]s. 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 service]]s 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 agent]]s''. In normal use, web [[browsers]], such as [[Internet Explorer]] and [[Mozilla Firefox|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 photographs, graphics, sounds, text, video, multimedia and interactive content including games, office applications and scientific demonstrations.

Through [[keyword (Internet search)|keyword]]-driven [[Internet research]] using [[search engine]]s like [[Yahoo! Search|Yahoo!]] and [[Google (search engine)|Google]], millions of people worldwide have easy, instant access to a vast and diverse amount of online information. Compared to [[encyclopedia]]s and traditional [[library|libraries]], the World Wide Web has enabled a sudden and extreme decentralization of information and data.

It is also easier, using the Web, 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 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 [[blog]]s, 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 [[software developer|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 service]]s 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===
{{see|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 [[Computer security|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 [[accountancy|accountant]] sitting at home can [[audit]] the books of a company based in another country, on a [[server (computing)|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 line]]s 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 Protocol|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===
{{seealso|Collaborative software}}

The low cost and nearly instantaneous sharing of ideas, knowledge, and skills has made [[collaboration|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]]). Films such as [[Zeitgeist (film)|''Zeitgeist'']], [[Loose Change (film)|''Loose Change'']] and [[Endgame (film)|''Endgame'']] have had extensive coverage on the Internet, while being virtually ignored in the mainstream media.

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===
{{details|File sharing}}

A [[computer file]] can be [[Electronic mail|e-mailed]] to customers, colleagues and friends as an [[E-mail attachment|attachment]]. It can be uploaded to a [[website]] or [[File Transfer Protocol|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 (computing)|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 signature]]s 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#Internet|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 [[webcast]]s. [[Podcast]]ing 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.

[[Webcam]]s 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)===
{{details|VoIP}}
VoIP stands for Voice over IP, where [[Internet Protocol|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 modem|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]] dialling 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 [[uninterruptible power supply|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 by region}}

==Internet access==<!-- This section is linked from [[Trackball]] -->
{{details|Internet access}}
{{wikibooks|Online linux connect}}
Common methods of home access include [[dial-up internet access|dial-up]], landline [[Broadband Internet access|broadband]] (over coaxial cable, [[fiber optic]] or copper wires), [[Wi-Fi]], [[Satellite Internet|satellite]] and [[3G]] technology [[mobile phone|cell phones]].

Public places to use the Internet include libraries and [[Internet cafe]]s, where computers with Internet connections are available. There are also [[Internet kiosk|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. [[Hotspot (Wi-Fi)|Hotspots]] providing such access include [[Wi-Fi#Commercial Wi-Fi|Wi-Fi cafes]], where would-be users need to bring their own wireless-enabled devices such as a [[laptop]] or [[Personal Digital Assistant|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 network]]s. 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.<ref>[http://www.bloomberg.com/apps/news?pid=10000082&sid=aQ0ZfhMa4XGQ&refer=canada "Toronto Hydro to Install Wireless Network in Downtown Toronto"]. Bloomberg.com. Retrieved 19-Mar-2006.</ref>

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

High-end mobile phones such as [[smartphone]]s generally come with Internet access through the phone network. Web browsers such as [[Opera (browser)|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 network service|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===
{{details|Internet 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]] 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.{{Fact|date=April 2007}}

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 activites===
The Internet has been a major source of leisure since before the World Wide Web, with entertaining social experiments such as [[MUD]]s and [[MOO]]s being conducted on university servers, and humor-related [[Usenet]] groups receiving much of the main traffic. Today, many [[Internet forum]]s have sections devoted to games and funny videos; short cartoons in the form of [[Flash animation|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 shooter]]s, from [[computer role-playing game|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 Arcade|GameSpy]] and [[MPlayer.com|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 [[Internet Relay Chat|chat]], [[instant messaging|messaging]] and e-mail to make and stay in touch with friends worldwide, sometimes in the same way as some previously had [[pen pal]]s. [[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 [[Internet operating system]]s, where users can access their files, folders, and settings via the Internet. An example of an [[opensource]] webOS is [[Eyeos]].

[[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]].<ref>[http://news.scotsman.com/topics.cfm?tid=914&id=1001802003 Scotsman.com News - Net abuse hits small city firms]</ref>

==Complex architecture ==
Many computer scientists see the Internet as a "prime example of a large-scale, highly engineered, yet highly complex system".<ref>Walter Willinger, Ramesh Govindan, Sugih Jamin, Vern Paxson, and Scott Shenker (2002). [http://www.pnas.org/cgi/content/full/99/suppl_1/2573 Scaling phenomena in the Internet]. In ''Proceedings of the National Academy of Sciences, 99'', suppl. 1, 2573–2580.</ref> The Internet is extremely heterogeneous. (For instance, [[data transfer rate]]s and physical characteristics of connections vary widely.) The Internet exhibits "[[Emergence|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.<ref>[http://seattletimes.nwsource.com/html/businesstechnology/2003667811_btrebuildnet16.html "Internet Makeover? Some argue it's time"]. The Seattle Times, April 16, 2007.</ref>

According to a June 2007 article in [[Discover (magazine)|''Discover'' magazine]], the combined weight of all the electrons moved within the Internet in a day is 0.2 millionths of an ounce.<ref>[http://discovermagazine.com/2007/jun/how-much-does-the-internet-weigh/?searchterm=weight%20internet "How Much Does The Internet Weigh?"]. Discover Magazine, June 2007.</ref> Others have estimated this at nearer 2 ounces (50 grams).<ref>[http://adamant.typepad.com/seitz/2007/06/the_sincerest_f.html How Much Does The Internet Weigh? -  The Unbearable Lightness Of Fact Checking]</ref>

==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 [[Compact disc|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|[[Disintermediation#Impact of Internet-related disintermediation upon various industries]] and [[Travel agency#The Internet threat]]}}

==The name ''Internet''==
{{details|Internet capitalization conventions}}
{{Wiktionarypar2|Internet|internet}}
''Internet'' is traditionally written with a [[majuscule|capital]] first letter, as it is a [[proper noun]]. The [[Internet Society]], the [[Internet Engineering Task Force]], the [[ICANN|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 (''Internet'').  Examples include ''[[The New York Times]]'', the ''[[Associated Press]]'', ''[[Time (magazine)|Time]]'', ''[[The Times of India]]'', ''[[Hindustan Times]]'', and ''[[Communications of the ACM]]''.

Others assert that the first letter should be in [[minuscule|lower case]] (''internet''), and that the specific article ''the'' is sufficient to distinguish "''the'' internet" from other internets. A significant number of publications use this form, including ''[[The Economist]]'', the [[Canadian Broadcasting Corporation]], 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'' meaning "an interconnected set of distinct networks", and ''Internet'' referring to the worldwide, publicly available [[Internet Protocol|IP]] internet. Under this distinction, ''the Internet'' is the familiar network through which [[website]]s exist; however, ''an internet'' can exist between any two remote locations.<ref>[http://what-is-what.com/what_is/internet.html What is the Internet?]</ref> Any group of distinct networks connected together is ''an'' internet; each of these networks may or may not be part of ''the'' Internet. The distinction was evident in many [[Request for Comments|RFCs]], books, and articles from the 1980s and early 1990s (some of which, such as RFC 1918, refer to "internets" in the plural), but has recently fallen into disuse.{{Fact|date=February 2007}} Instead, the term ''[[intranet]]'' is generally used for private networks, whether they are connected to the Internet or not (see also [[extranet]]).

Some people use the lower-case term as a medium (like radio or newspaper, e.g. ''I've found it on the internet''), and first letter capitalized as the global network.

==See also==
{{sisterlinks|Internet}}
{{Main|List of basic Internet topics|List of Internet topics}}

===Major aspects and issues===
*[[Internet democracy]]
*[[History of the Internet]]
*[[Net neutrality]]
*[[Internet privacy|Privacy on the Internet]]
*[[Internet phenomenon]]

===Functions===
*[[E-mail]]
*[[File-sharing]]
*[[Instant messaging]]
*[[Internet fax]]
*[[World Wide Web]]
*[[Voice over IP]]
*[[Mobile VoIP]]

===Underlying infrastructure===
*[[Internet Protocol]] (IP)
*[[Internet Service Provider]] (ISP)

===Regulatory bodies===
*[[Internet Assigned Numbers Authority]] (IANA)
*[[Internet Corporation for Assigned Names and Numbers]] ([[ICANN]])

==Notes==
{{reflist|2}}

==References==
*[http://www.osce.org/item/13570.html Media Freedom Internet Cookbook] by the [[OSCE Representative on Freedom of the Media]] Vienna, 2004
*[http://www.livinginternet.com  Living Internet]—Internet history and related information, including information from many creators of the Internet
*[http://www.firstmonday.org/ First Monday] peer-reviewed journal on the Internet
*[http://discovermagazine.com/2007/jun/how-much-does-the-internet-weigh How Much Does The Internet Weigh?] by Stephen Cass, [[Discover (magazine)|Discover]] 2007
*Rehmeyer, Julie J. 2007. Mapping a medusa: The Internet spreads its tentacles. Science News 171(June 23):387-388. Available at http://www.sciencenews.org/articles/20070623/fob2.asp . 
*Castells, M. 1996. Rise of the Network Society. 3 vols. Vol. 1. Cambridge, MA: Blackwell Publishers. 
*Castells, M. (2001), “Lessons from the History of Internet”, in “The Internet Galaxy”, Ch. 1, pp 9-35. Oxford Univ. Press.

==External links==
*[http://www.wired.com/wired/archive/13.08/intro.html "10 Years that changed the world" — Wired looks back at the evolution of the Internet over last 10 years]
*[http://cyber.law.harvard.edu/home/ Berkman Center for Internet and Society at Harvard]
*[http://www.livinginternet.com/ A comprehensive history with people, concepts and  quotations]
*[http://archives.cbc.ca/IDD-1-75-1738/science_technology/internet/ CBC Digital Archives—Inventing the Internet Age]
*[http://www.internetvalley.com/archives/mirrors/cerf-how-inet.txt How the Internet Came to Be]
*[http://www.searchandgo.com/articles/internet/net-explained-1.php Internet Explained]
*[http://www.internettrafficreport.com/ Global Internet Traffic Report]
*[http://www.isoc.org/internet/history/brief.shtml The Internet Society History Page]
*[http://www.ietf.org/rfc/rfc801.txt RFC 801, planning the TCP/IP switchover]
*[http://www.youtube.com/watch?v=b1A9lYC3g-0 Archive CBC Video Circa 1990 about the Internet]
*[http://abandonshack.com/?page_id=20 "The beginners guide to the internet."]
*[http://www.warriorsofthe.net/ "Warriors of the net - A movie about the internet."]
*[http://www.littletechshoppe.com/ns1625/nshist47.html "History of Nova Scotia-First on the Net"]
*[http://www.webmastermind.com.au/ Digital Economy] For additional information on the digital economy

[[Category:Internet| ]]
[[Category:Telecommunications]]