The Internet is a global system of interconnected computer networks A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network that use the standardized Internet Protocol Suite The Internet Protocol Suite is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard. Today's IP networking (TCP/IP). 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 Copper is a chemical element with the symbol Cu (Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color. It is used as a thermal conductor, an electrical conductor, a building material, and a wires, fiber-optic An optical fiber is a glass or plastic fiber that carries light along its length. Fiber optics is the overlap of applied science and engineering concerned with the design and application of optical fibers. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data cables, wireless Wireless communication is the transfer of info. over a distance without the use of electrical conductors or "wires". The distances involved may be short or long (thousands or millions of kilometers for radio communications). When the context is clear, the term is often shortened to "wireless". Wireless communication is connections, and other technologies.

The Internet carries a vast array of information Information as a concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control, data, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation resources and services, most notably, the inter-linked hypertext Hypertext is text, displayed on a computer, with references to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Other means of interaction may also be present, such as a bubble with text appearing when documents of the World Wide Web The World Wide Web is a system of interlinked hypertext documents accessed via the Internet. With a Web browser, one can view Web pages that may contain text, images, videos, and other multimedia and navigate between them using hyperlinks. Using concepts from earlier hypertext systems, the World Wide Web was invented in 1989 by the English (WWW) and the infrastructure to support electronic mail Electronic mail, often abbreviated as email or e-mail, is a method of exchanging digital messages, designed primarily for human use. E-mail systems are based on a store-and-forward model in which e-mail computer server systems accept, forward, deliver and store messages on behalf of users, who only need to connect to the e-mail infrastructure,, in addition to popular services such as online chat Online chat can refer to any kind of communication over the Internet, but is primarily meant to refer to direct one-on-one chat or text-based group chat , using tools such as instant messengers, Internet Relay Chat, talkers and possibly MUDs. The expression online chat comes from the word chat which means "informal conversation", file transfer File transfer is a generic term for the act of transmitting files over a computer network or the Internet. There are numerous ways and protocols to transfer files over a network. Computers which provide a file transfer service are often called file servers. Depending on the client's perspective the data transfer is called uploading or downloading and file sharing File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media , documents, or electronic books. It may be implemented in a variety of storage, transmission, and distribution models. Common methods are manual sharing using removable media, centralized computer file server, online gaming An online game is a game played over some forms of computer network. At the present, this almost always means the Internet or equivalent technology; but games have always used whatever technology was current: modems before the internet, and hard wired terminals before modems. The expansion of online gaming has reflected the overall expansion of, and Voice over Internet Protocol Voice over Internet Protocol is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, (VoIP) person-to-person communication via voice and video.

The origins of the Internet reach back to the 1960s when the United States funded research projects of its military agencies to build robust, fault-tolerant and distributed computer networks. This research and a period of civilian funding of a new U.S. backbone by the National Science Foundation The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health. With an annual budget of about $6.02 billion (fiscal year 2008), NSF funds approximately 20 percent of all spawned worldwide participation in the development of new networking technologies and led to the commercialization of an international network in the mid 1990s, and resulted in the following popularization of countless applications in virtually every aspect of modern human life. By 2009, an estimated quarter of Earth's population uses the services of the Internet (see Growth).

Terminology

The terms Internet and World Wide Web are often used in everyday speech without much distinction. However, the Internet and the World Wide Web The World Wide Web is a system of interlinked hypertext documents accessed via the Internet. With a Web browser, one can view Web pages that may contain text, images, videos, and other multimedia and navigate between them using hyperlinks. Using concepts from earlier hypertext systems, the World Wide Web was invented in 1989 by the English are not one and the same. The Internet is a global data communications system. It is a hardware and software infrastructure that provides connectivity between computers A computer is a machine that manipulates data according to a set of instructions. In contrast, the Web is one of the services communicated via the Internet. It is a collection of interconnected documents and other resources The concept of resource is primitive in the Web architecture, and is used in the definition of its fundamental elements. The term was first introduced to refer to targets of Uniform Resource Locators , but its definition has been further extended to include the referent of any Uniform Resource Identifier (RFC 3986), or Internationalized Resource, linked by hyperlinks In computing, a hyperlink is a reference in a document to an external piece of information. The most common usage is in the Internet to browse through web pages: some text in the current document is highlighted so that when clicked, the browser automatically displays another page or changes the current page to show the referenced content. The and URLs In computing, a Uniform Resource Locator is a type of Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. In popular usage and in many technical documents and verbal discussions it is often incorrectly used as a synonym for URI. In popular language, a URL is also referred.^[1]

The term the Internet, when referring to the Internet, has traditionally been treated as a proper noun Lexical categories are defined in terms of how their members combine with other kinds of expressions. The syntactic rules for nouns differ from language to language. In English, nouns may be defined as those words which can occur with articles and attributive adjectives and can function as the head of a noun phrase and written with an initial capital letter Capital letters or majuscules [IPA pronunciation: /məˈdʒʌskjuls, ˈmædʒəˌskjuls/], in the Roman alphabet A, B, C, D, etc., may also be called capitals, or caps. Upper case, upper-case, or uppercase is also often used in this context as synonym of capital. Manual typesetters kept them in the upper drawers of a desk or in the upper type case,. There is a trend to regard it as a generic term or common noun and thus write it as "the internet", without the capital.

History

Creation

The USSR The Union of Soviet Socialist Republics , occasionally called the United Soviet Socialist Republic, was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the Russian: Союз Советских Социалистических Республик​ (help·info), tr. Soyuz Sovetskikh's launch of Sputnik The Sputnik program was a series of robotic spacecraft missions launched by the Soviet Union. The first of these, Sputnik 1, launched the first human-made object to orbit the Earth. That launch took place on October 4, 1957 as part of the International Geophysical Year and demonstrated the viability of using artificial satellites to explore the spurred the United States to create the Advanced Research Projects Agency, known as ARPA, in February 1958 Categories: 1958 | 1950s in science | Years in science to regain a technological lead.^[2][3] ARPA created the Information Processing Technology Office (IPTO) to further the research of the Semi Automatic Ground Environment The Semi-Automatic Ground Environment was an automated control system for tracking and intercepting enemy bomber aircraft used by NORAD from the late 1950s into the 1980s. In later versions, the system could automatically direct aircraft to an interception by sending commands directly to the aircraft's autopilot (SAGE) program, which had networked country-wide radar Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for radio detection and ranging. The term has since entered the English systems together for the first time. J. C. R. Licklider Joseph Carl Robnett Licklider , known simply as J.C.R. or "Lick" was an American computer scientist, considered one of the most important figures in computer science and general computing history was selected to head the IPTO.

Licklider moved from the Psycho-Acoustic Laboratory at Harvard University Harvard University is a private university located in Cambridge, Massachusetts, and a member of the Ivy League. Founded in 1636 by the colonial Massachusetts legislature, Harvard is the oldest institution of higher learning in the United States. It is also the first and oldest corporation in North America. Administratively, Harvard comprises ten to MIT The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts, United States. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological research. MIT is one of two private land-grant universities[b] and is also a sea- in 1950 Categories: 1950 | 1950s in science | Years in science , after becoming interested in information technology Information technology , as defined by the Information Technology Association of America (ITAA), is "the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware." IT deals with the use of electronic computers and computer software to. At MIT, he served on a committee that established Lincoln Laboratory MIT Lincoln Laboratory, also known as Lincoln Lab, is a federally funded research and development center managed by the Massachusetts Institute of Technology and primarily funded by the United States Department of Defense. Lincoln Lab is located at Hanscom Air Force Base in the town of Lexington, Massachusetts, and was founded in 1951 and worked on the SAGE project. In 1957 Categories: 1957 | 1950s in science | Years in science he became a Vice President at BBN BBN Technologies is a high-technology company which provides research and development services. BBN is based next to Fresh Pond in Cambridge, Massachusetts, USA. It is perhaps best known for its work in the development of packet switching (including the ARPANET and the Internet) and for its 1978 acoustical analysis for the House Select Committee, where he bought the first production PDP-1 The PDP-1 was the first computer in Digital Equipment Corporation's PDP series and was first produced in 1960. It is famous for being the computer most important in the creation of hacker culture, at MIT, BBN and elsewhere. The PDP-1 was also the original hardware for playing history's first computerized video game, Steve Russell's Spacewar! computer and conducted the first public demonstration of time-sharing Time-sharing is sharing a computing resource among many users by multitasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major historical shift in the history of computing. By allowing a large number of users to interact simultaneously on a single computer, time-sharing dramatically.

At the IPTO, Licklider got Lawrence Roberts Lawrence G. Roberts received the Draper Prize in 2001 "for the development of the Internet" along with Leonard Kleinrock, Robert Kahn, and Vinton Cerf to start a project to make a network, and Roberts based the technology on the work of Paul Baran Paul Baran was one of the three inventors of packet-switched networks, along with Donald Davies and Leonard Kleinrock. He was born in Grodno (then Poland) and his family moved to Philadelphia in 1928. Baran did undergraduate work at Drexel University, obtained his Masters degree in Engineering from UCLA in 1959 and began working for the RAND,^[4] who had written an exhaustive study for the U.S. Air Force The United States Air Force is the aerial warfare branch of the U.S. armed forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on 18 September 1947. It is the most recent branch of the U.S. military to be formed that recommended packet switching Packet switching is a network communications method that groups all transmitted data, irrespective of content, type, or structure into suitably-sized blocks, called packets. The network over which packets are transmitted is a shared network which routes each packet independently from all others and allocates transmission resources as needed. The (as opposed to circuit switching In telecommunications, a circuit switching network is one that establishes a circuit between nodes and terminals before the users may communicate, as if the nodes were physically connected with an electrical circuit) to make a network highly robust and survivable. After much work, the first two nodes of what would become the ARPANET The ARPANET created by ARPA of the United States Department of Defense during the Cold War, was the world's first operational packet switching network, and the predecessor of the global Internet were interconnected between UCLA The University of California, Los Angeles is a public ivy research university located in Westwood, Los Angeles, California, United States. It was founded in 1919 and is the second-oldest general-purpose campus in the University of California system and SRI International SRI International, founded as Stanford Research Institute, is one of the world's largest contract research institutes. Based in the United States, the trustees of Stanford University established it in 1946 as a center of innovation to support economic development in the region. It was later incorporated as an independent non-profit organization (SRI) 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 The General Post Office was officially established in England in 1660 by Charles II and it eventually grew to combine the functions of both the state postal system and telecommunications carrier. Similar General Post Offices were established across the British Empire. In 1969 the GPO was abolished and the assets transferred to The Post Office,, Telenet Telenet was a packet switched network which went into service in 1974. It was the first publicly available commercial packet-switched network service, DATAPAC and TRANSPAC collaborated to create the first international packet-switched network service. In the UK, this was referred to as the International Packet Switched 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-based wide-area network was operational by January 1, 1983 when all hosts on the ARPANET were switched over from the older NCP protocols. In 1985, the United States' National Science Foundation (NSF) commissioned the construction of the NSFNET, a university 56 kilobit/second network backbone using computers called "fuzzballs" by their inventor, David L. Mills. The following year, NSF sponsored the conversion to a higher-speed 1.5 megabit/second network. 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 (ISPs) 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 an array of standardized commercial routers from many companies, the availability of commercial Ethernet equipment for local-area networking, and the widespread implementation and rigorous standardization of TCP/IP on UNIX and virtually every other common operating system.

Growth

Although the basic applications and guidelines that make the Internet possible had existed for almost two decades, the network did not gain a public face until the 1990s. On 6 August 1991, CERN, a pan European organisation for particle research, 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, patterned after HyperCard and built using the X Window System. 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 percent per year, with a brief period of explosive growth in 1996 and 1997.^[5] 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. ^[6]

Using various statistics, Advanced Micro Devices estimated the population of Internet users to be 1.5 billion as of January 2009.^[7]

Technical foundation

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 and provides the foundation for its scalability and success.

The responsibility for the architectural design of the Internet software systems has been delegated to the Internet Engineering Task Force (IETF).^[8] 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 a series of publications each of which is called a Request for Comment (RFC), freely available on the IETF web site. The principal methods of networking that enable the Internet are contained in specially designated RFCs that constitute the Internet Standards.

These standards describe a framework 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 Application Layer, the space for the application-specific networking methods used in software applications, e.g., a web browser program, and just below it is the Transport Layer which connects applications on different hosts via the network (e.g., client-server model) with appropriate data exchange methods. Underlying these layers are the actual networking technologies, consisting of two layers. The Internet Layer enables computers to identify and locate each other via Internet Protocol (IP) addresses, and allows them to connect to one-another via intermediate (transit) networks. Lastly, at the bottom of the architecture, is a software layer that provides connectivity between hosts on the same local network link (therefor called Link Layer), such as a local area network (LAN) or a dial-up connection. The model, also known as TCP/IP, is designed to be independent of the underlying hardware which the model therefore does not concern itself with in any detail. Other models have been developed, such as the Open Systems Interconnection (OSI) model, but they are not compatible in the details of description, nor implementation, but many similarities exist and the TCP/IP protocols are usually included in the discussion of OSI networking.

The most prominent component of the Internet model is the Internet Protocol (IP) which provides addressing systems (IP addresses) for computers on the Internet. IP enables internetworking and essentially establishes the Internet itself. 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 which is estimated to enter its final stage in approximately 2011.^[9] A new protocol version, IPv6, was developed which provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6 is currently in commercial deployment phase around the world and Internet address registries (RIRs) have begun to urge all resource managers to plan rapid adoption and conversion.^[10]

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

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.

Today's Internet

Internet structure

The Internet and its structure have been studied extensively. For example, it has been determined that both 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 GEANT, GLORIAD, Internet2 (successor of the Abilene Network), and the UK's national research and education network JANET. These in turn are built around smaller networks (see also the list of academic computer network organizations).

Many computer scientists describe 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 hierarchical sub-network that can theoretically be extended infinitely (disregarding the programmatic limitations of the IPv4 protocol). Principles of this architecture date back to the 1960s and it might not be a solution best suited to modern needs. 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]

Computer network diagrams often represent the Internet using a cloud symbol from which network communications pass in and out.^[15]

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 (IP) addresses, and protocol port and parameter numbers. A globally unified name space (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 origin of the Internet, 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 (28.6% of Web visitors) the most requested languages on the World Wide Web are Chinese (20.3%), Spanish (8.2%), Japanese (5.9%), French and Portuguese (4.6%), German (4.1%), Arabic (2.6%), Russian (2.4%), and Korean (2.3%).^[16]

By region, 41% of the world's Internet users are based in Asia, 25% in Europe, 16% in North America, 11% in Latin America and the Caribbean, 3% in Africa, 3% in the Middle East and 1% in Australia.^[17]

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.

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.

Pictures, documents and other files can be sent as e-mail attachments. E-mails can be cc-ed to multiple e-mail addresses.

The World Wide Web

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, Firefox, Opera, Apple Safari, and Google Chrome, 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 organizations 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 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.

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 or wiki software with, initially, very little content. Contributors to these systems, who may be paid staff, members of a club or other organization 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 their 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.

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 share ideas, but the wide reach of the Internet allows such groups to easily form in the first place. An example of this is the free software movement, which has produced, among other programs, Linux, Mozilla Firefox, and OpenOffice.org.

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 exchanged even more quickly and conveniently than via e-mail. Extensions to these systems may allow files to be exchanged, "whiteboard" drawings to be shared or 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 make their contributions.

Business and project teams can share calendars as well as documents and other information. Such collaboration occurs in a wide variety of areas including scientific research, software development, conference planning, political activism and creative writing.

Social and political collaboration is also becoming more widespread as both Internet access and computer literacy grow. From the flash mob 'events' of the early 2000s to the use of social networking in the 2009 Iranian election protests, the Internet allows people to work together more effectively and in many more ways than was possible without it.

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 for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—usually 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 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.

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 downloaded and played back on a computer or shifted to a portable media 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, traffic at a local roundabout or monitor their own premises, live and in real time. Video chat rooms and video conferencing are also popular with many uses being found for personal webcams, with and without two-way sound.

YouTube was founded on 15 February 2005 and is now the leading website for free streaming video with a vast number of users. It uses a flash-based web player to stream and show video files. Registered users may upload an unlimited amount of video and build their own personal profile. YouTube claims that its users watch hundreds of millions, and upload hundreds of thousands, of videos daily.^[18]

Internet Telephony (VoIP)

VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underlies all Internet communication. The idea began in the early 1990s with walkie-talkie-like voice applications for personal computers. 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 voice traffic, VoIP can be free or cost much less than a traditional telephone call, especially over long distances and especially for those with always-on Internet connections such as cable or ADSL.

VoIP is maturing into a competitive alternative to traditional telephone service. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple, inexpensive VoIP network adapters are available that eliminate the need for a personal computer.

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 backup power source for the phone equipment and the Internet access devices.

VoIP has also become increasingly popular for gaming applications, as a form of communication between players. Popular VoIP clients for gaming include Ventrilo and Teamspeak. Wii, PlayStation 3, and Xbox 360 also offer VoIP chat features.

Internet by region

Internet access

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.^[19]

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

See also: Sociology of the Internet

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.

Digital Natives

The first generation is now being raised with widespread availability of Internet connectivity, with consequences for privacy, identity, and copyright concerns. These "Digital Natives" face a variety of concerns that were not present for prior generations.

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 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^[20] 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 game play 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. 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.^[21]

Market

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.

See also

Textbooks from Wikibooks Quotations from Wikiquote Source texts from Wikisource Images and media from Commons News stories from Wikinews

• List of inventions by the military that are now in mass use
• Demographics of the Internet
• Digital rights
• Internet democracy
• Network Neutrality
• Freedom of information
• Privacy on the Internet
• Internet phenomenon
• Internet bias
• List of cable Internet providers
• Electronic publishing

Notes

1. ^ "Links". HTML 4.01 Specification. World Wide Web Consortium. HTML 4.01 Specification. http://www.w3.org/TR/html401/struct/links.html#h-12.1. Retrieved on 2008-08-13. "[T]he link (or hyperlink, or Web link) [is] the basic hypertext construct. A link is a connection from one Web resource to another. Although a simple concept, the link has been one of the primary forces driving the success of the Web."
2. ^ "ARPA/DARPA". Defense Advanced Research Projects Agency. http://www.darpa.mil/body/arpa_darpa.html. Retrieved on 2007-05-21.
3. ^ "DARPA Over the Years". Defense Advanced Research Projects Agency. http://www.darpa.mil/body/overtheyears.html. Retrieved on 2007-05-21.
4. ^ Baran, Paul (1964). On Distributed Communications. http://www.rand.org/pubs/research_memoranda/RM3767.
5. ^ Coffman, K. G; Odlyzko, A. M. (1998-10-02) (PDF). The size and growth rate of the Internet. AT&T Labs. http://www.dtc.umn.edu/~odlyzko/doc/internet.size.pdf. Retrieved on 2007-05-21.
6. ^ Comer, Douglas (2006). The Internet book. Prentice Hall. p. 64. ISBN 0132335530.
7. ^ "AMD 50x15 - World Internet Usage". 50x15.com. http://www.50x15.com/en-us/internet_usage.aspx. Retrieved on 2009-06-20.
8. ^ "IETF Home Page". Ietf.org. http://www.ietf.org/. Retrieved on 2009-06-20.
9. ^ Huston, Geoff. "IPv4 Address Report, daily generated". http://www.potaroo.net/tools/ipv4/index.html. Retrieved on 2009-05-20.
10. ^ Notice of Internet Protocol version 4 (IPv4) Address Depletion
11. ^ Walter Willinger, Ramesh Govindan, Sugih Jamin, Vern Paxson, and Scott Shenker (2002). Scaling phenomena in the Internet, in Proceedings of the National Academy of Sciences, 99, suppl. 1, 2573–2580
12. ^ "Internet Makeover? Some argue it's time". The Seattle Times, April 16, 2007.
13. ^ "How Much Does The Internet Weigh?". Discover Magazine, June 2007.
14. ^ "Weighing The Web". 2007-06-01. http://adamant.typepad.com/seitz/2007/06/the_sincerest_f.html. Retrieved on 2008-05-26.
15. ^ The Internet Cloud
16. ^ Internet World Stats, updated December 31, 2008
17. ^ World Internet Usage Statistics News and Population Stats updated December 31, 2008
18. ^ "YouTube Fact Sheet". YouTube, LLC. http://www.youtube.com/t/fact_sheet. Retrieved on 2009-01-20.
19. ^ "Toronto Hydro to Install Wireless Network in Downtown Toronto". Bloomberg.com. Retrieved 19-Mar-2006.
20. ^ "Finland censors anti-censorship site". The Register. 2008-02-18. http://www.theregister.co.uk/2008/02/18/finnish_policy_censor_activist/. Retrieved on 2008-02-19.
21. ^ Scotsman.com News - Net abuse hits small city firms

References

• Media Freedom Internet Cookbook by the OSCE Representative on Freedom of the Media Vienna, 2004
• Living Internet—Internet history and related information, including information from many creators of the Internet
• First Monday peer-reviewed journal on the Internet
• How Much Does The Internet Weigh? by Stephen Cass, 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.
• RFC 1122, Requirements for Internet Hosts—Communication Layers, IETF, R. Braden (Ed.), October 1989
• RFC 1123, Requirements for Internet Hosts—Application and Support, IETF, R. Braden (Ed.), October 1989

External links

• The Internet (National Science Foundation)
• "10 Years that changed the world" — Wired looks back at the evolution of the Internet over last 10 years
• Berkman Center for Internet and Society at Harvard
• CBC Digital Archives—Inventing the Internet Age
• How the Internet Came to Be
• The Internet Society History Page
• RFC 801, planning the TCP/IP switchover
• Preparing Europe’s digital future - i2010 Mid-Term Review
• Manjoo, Farhad - The Unrecognizable Internet of 1996 - Slate

Categories: Internet | Mass media | Telecommunications | American inventions | Scientific revolution

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• Internet
• Internet Explorer
• Internet Terminology
• Category:Internet Terminology
• Computers: Internet: On the Web: Web Applications: Bookmark Managers

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