The Internet is an international web of interconnected government, education, and business computer network. A person at a computer terminal or personal computer with the proper software communicates across the Internet by placing data in an Internet Protocol (IP) packet--an electronic envelope--and "addressing" the packet to a particular destination on the Internet. Communications software on the intervening networks "read" the addresses on packets moving through the Internet and forward the packets toward their destinations. From a thousand or so networks in the mid-1980s the Internet has grown to tens of thousands of connected networks and is available to millions of people worldwide.
The World Wide Web (WWW), often referred to simply as the Web, is a service that allows computer users to quickly and easily navigate the Internet, the international collection of thousands of interconnected computer networks. Using hypertext links for organizing and displaying information on the Internet, the Web enables users to jump from one document to another, simply by pointing to a highlighted phrase ("link"), then clicking a mouse button. For example, a person reading a document on AIDS may come to a highlighted reference to tuberculosis. The tuberculosis document may be stored on the same computer (Web site) or on a computer on another continent. In either case, moments after the person clicks on the highlighted reference, the tuberculosis document appears on the screen.
Computer networks are interconnections of many computers for the purpose of sharing resources. They allow communication between users through electronic mail and "bulletin boards," and they provide access to unique databases. They can be thought of as information highways over which data are transported. They speed up processing and databasing in busy systems, reduce costs (as in eliminating paperwork), and offer many other conveniences. Networks are changing the computing paradigm from "number-crunching" to communicating. In turn they have spawned industries such as the online industry, a collection of organizations providing information and communication services to remote customers via dial-up modems.
Cyberspace is a catchword for the interactive computing and communications base available on the Internet. Science fiction writer William Gibson coined the word in Neuromancer (1984), a novel in which "hackers" connect their brains directly to a computer network where the data of multinational corporations are represented as geometrical shapes in a virtual reality landscape. The hacker-heroes of Gibson's novels (and of the works of Gibson's imitators) travel in this computer-network world as if it were a real world that they could apprehend with their senses.
Sponsored by the U.S. Department of Defense Advanced Research Projects Agency, ARPANET was a wide area network (see WAN) that linked computers at research centers around the United States. It was the first computer network and the forerunner of today's Internet.
Online, interactive services are information and transactional services that are delivered to individual users, through a personal computer or other electronic devices, using a two-way telecommunications system such as a telephone or cable television. In conventional online services, "host" computers or "servers" store database information and transactional content. A system operator enables the user to "log on" and navigate through the system by means of a keyboard or mouse. The term "videotex" was first applied to such services, but following the failure of many U.S. videotex projects in the late 1980s the term began to fall out of favor, and the terms "online services" and "interactive services" came to be used instead.
A wide area network (WAN) is a computer network that uses telephone lines, or telephone lines and satellites, to connect computers over distances greater than those possible with local area networks. There are two types of WAN: centralized and distributed. A centralized WAN has a computer called a server as its core unit; it stores application software, databases, and documents and "serves" them to people at remote terminals. A distributed WAN has more than one server computer, each able to transmit and control data. Special-purpose computers called routers can be used to connect a number of LANs to form a WAN--or to connect several small WANs to form a larger WAN.
The Internet owes its unusual design and architecture to its origins in the U.S. Defense Department's ARPANET project in 1969 (the name derives from the Advanced Research Project Agency, the research group within the Pentagon responsible for the project). Its planners sought to design a network that could withstand partial destruction and still function. They reasoned that centralized control of data flow through one or a few "hub" computers would leave the system too open to disruption. Every computer on the network should be able to communicate, as a peer, with every other computer. Thus, if part of the network were destroyed, the other parts would automatically reroute communications through different pathways. Because many factors--power outages, overtaxed telecommunications lines, equipment failure--can degrade a network's performance, the ARPANET solution became the preferred solution for most future networkers.
Local area networks (single-site computer networks) proliferated in the 1980s in universities and, increasingly, in businesses and corporations. The majority of these networks used the same communications protocols as ARPANET. The usefulness of internetwork communication and data sharing became self-evident to the managers of these new networks, and many of them linked up to other networks.
br
In the late 1980s the National Science Foundation (NSF) built five supercomputer centers to give any academic researcher access to high-power computers (see National Center for Supercomputing Applications). The NSF built its own network, based on IP technology, to connect the five centers, and individual university networks were chained together and linked to the closest one. Soon the network connections were being used for purposes unrelated to the centers, such as electronic mail (e-mail), and Internet traffic is now routed through a loose consortium of network providers.
The Internet is also a repository of information for businesses and a data-sharing viaduct for thousands of discussion groups with specialized interests. The U.S. government posts more and more information on the Internet, such as Commerce Department data and new patent filings, and many universities are converting large libraries to electronic form. Cornell University, for example, has an ongoing project to convert 100,000 books, printed over the past century, on the development of American infrastructure--books on bridges, roads, and other public works.
Businesses advertise and market on the Internet. Online catalogs and advertising interspersed with directory-type information provide the most opportunity. Online ordering of products is becoming more and more popular. Protection of copyrighted material is a problem, however, because anyone can "download" (electronically copy) data from the Internet. Some companies have explored encrypting data for sale on the Internet, providing decoding keys only to buyers of the data, but this scheme will not prevent the buyers from "repackaging" and reselling the data.
Internet growth has been fueled by individual users with modem-equipped personal computers. Most of them subscribe to local networks that provide a connection to the wider Internet. Many users, as well as businesses, create their own "home pages"--points of access that allow anyone on the Internet to view and download information. Internet growth has also been fueled by the development of the World Wide Web: a collection of thousands of independently owned computers, called Web servers, that are linked worldwide. Using software programs such as Netscape, individuals can enter the Web through local "providers" or through the large online services and "browse" or "surf" the Internet with increasing ease and rapidity through a system of hypertext links.
Businesses are creating "intranets" on their own private networks. Using Internet technology, they can link traditional directory, e-mail, and other networking software applications. The Internet can connect warehouses, manufacturing sites, retail stores, and customers easily by using simple browsers freely provided on practically every computer now sold. Because of the Internet's explosive growth, however, telecommunications companies are struggling to keep up with the demand. (Use of the Internet during the business day and in the early evening has caused some pundits to call the World Wide Web the "World Wide Wait.").
Researchers having to conduct highly complex projects require much greater capacity than the current Internet provides, however, and in 1995 the NSF began to meet such needs. It did so by converting the Internet "backbone"--the electronic pipeline between the five supercomputer communications hubs--into a system many times more powerful than the current Internet but available only to medical researchers, astrophysicists, and other such specialists. The managers and users of this new network, called the Very-High-Performance Backbone Network Service, are increasing its fiber-optic linkages and adding technologically advanced switches and routers to the system.
Philip Storey
Bibliography: Crumlish, C., The ABCs of the Internet (1996); Hafner, K., and Lyon, M., Where Wizards Stay Up Late (1996); Holt, W. H., and Morgan, R. J., The Web Dictionary (1996); Kraynak, Joe, The Big Basics Book of the Internet (1996); Norbert, A., and O'Neill, J., Transforming Computer Technology (1996); Pomeroy, B., BeginnerNet (1996); Rothman, D., Networld! (1997); Stefik, Mark, Internet Dreams (1997); Virginia Space Grant Consortium Staff, The Educator's Guide to the Internet (1997).
Top
The Web was developed in 1990 at the European Organization for Nuclear Research (CERN), as a way for scientists to share documents. By 1995 it was the fastest-growing service on the Internet. At present, the Web is being used mainly as an information resource, but numerous additional applications are possible. For example, a growing number of companies are establishing Web sites to promote products and sell merchandise. .
Top
In a computer network the individual stations, called "nodes," may be computers, terminals, or communication units of various kinds. Networks that are contained within a building or small geographical area are called local-area networks, or LANs. They usually operate at relatively high speeds. The Ethernet, Token Ring, and FDDI (fiber distributed data interface; see fiber optics) are examples of transmission technologies often used in LANs. Larger networks, called wide-area networks, or WANs, use a variety of transmission media, such as telephone lines, to span states, countries, or the entire globe (see Internet).
Networks are designed and constructed in layers. Each layer is defined by a standard, called a protocol, that defines how information is organized and transmitted from one node to another. The lowest layers define how bits of data are packaged, while the highest layers define how the data are fed into an application running on a desktop or mainframe computer. There are two basic approaches to data-layer protocol design: packet-switched and circuit-switched. The packet-switched approach is most popular in LANs because of its reliability and simplicity. Perhaps the most widely known is the packet-switched transmission control protocol/Internet protocol (TCP/IP) used by the Internet.
Circuit-switched approaches have traditionally been used by telephone companies to implement WAN connections. This has been changing, however, as companies convert to digital communications compatible with computers. For example, the asynchronous transfer mode (ATM) protocol is a hybrid between circuit- and packet-switched methods. The ATM divides data into small packets called cells and then routes these cells over a virtual circuit, much like an ordinary telephone call. A virtual circuit is a point-to-point connection that may send data over different physical links during the communication session. The circuit is made "virtual" because the user never knows that the cells are routed over different links throughout the session. In either approach, one computer will not be able to communicate with another unless they use the same protocol. This problem has been addressed by vendors of devices--called bridges, routers, and hubs--that convert from one protocol to another. A bridge connects networks, while a router is a more "intelligent" bridge that can find nodes on the network as well. A hub is often a sophisticated computer that does conversions, changes transmission speeds, and routes data to a variety of nodes.
Nodes have telephone numbers that uniquely identify the location (in network geography) of a computer on the Internet. For example, the IP (Internet protocol) of a computer might be 131.120.1.50. Because such numbers are difficult to remember, a naming convention has been invented by users. Names such as "[email protected]" are automatically converted into an IP number by a name-server program. Here, "joe" is the name of the user, "mist" is the name of the computer, "ece" is the name of a department (electrical and computer
Top
Gibson's cyberspace--fleshed out in his subsequent novels Count Zero and Mona Lisa Overdrive--was seen by many in the computing community of the 1980s as a metaphor for the way people working for universities, corporations, and governments interacted with one another through computer networks. By the early 1990s the word had passed into general usage and is synonymous with the Internet.
Philip Storey
Bibliography: Benedikt, Michael L., Cyberspace: First Steps (1991); Hamit, Francis, Virtual Reality and the Exploration of Cyberspace (1993); Krueger, Myron, Artificial Reality, 2d ed. (1991); Thalmann, N. M. and D., Virtual Worlds and Multimedia (1993).
Top
In the 1960s, the Defense Department was interested in creating a nonhierarchical, geographically dispersed communications system that would allow the military to communicate even if one or more key links were destroyed during a nuclear war. At that time, no standard computer operating system existed; thus, computers generally could not communicate with one another. Academic computer scientists were hired to develop the network, which was launched in 1969 with four nodes, or sites: the University of California at Los Angeles; the University of California, Santa Barbara; Stanford Research Institute; and the University of Utah. By 1971, ARPANET had expanded to 23 sites; by 1981, to over 200.
Although the original purpose of ARPANET was restricted to Defense Department projects, it quickly became a way for academics to communicate on a myriad of nondefense topics. Scientists without Defense Department clearance were denied access to ARPANET, so in 1979 an academic network, Usenet News, began; its nodes eventually connected with those of ARPANET.
Top
The international web of interconnected computer networks known as the Internet--and especially its World Wide Web segment--has become intertwined with online services. Indeed, most online service operators offer their customers access to the Web and have been integrating their own interactive features in the Web. The most popular features of the majority of online services (similar to the Web) are communications and messaging services, including personal electronic mail (e-mail), chat-lines, and bulletin board systems (BBS). In addition, information can be retrieved from databases and people can conduct banking transactions, go shopping, make purchases or airline and hotel reservations, pay bills, and play video games.
Information providers and service providers (collectively called content suppliers) maintain and update database services. Online systems can provide information in various formats, including highly graphical multimedia displays. Content is usually displayed page by page or by "scrolling" through lines of text.
Online systems originated in Europe in the 1970s. At that time government-owned telephone agencies sought to promote the use of computer time-sharing networks. In France the large online service Minitel was launched in the early 1980s by the nation's government, which funded distribution of small, computerlike "Minitel" terminals. French technology was used thereafter on smaller systems in Italy, Ireland, and other countries.
In the United States, online systems were originally promoted by the newspaper industry, which sought to create "electronic publications," offering news and ads through special terminals hooked up to TV monitors (see teletext). Several business-oriented online services were created during this period. The reorganization of the U.S. telephone industry following the American Telephone and Telegraph Co. divestiture in 1984 also affected the development of online systems. Then, with the growing popularity of the personal computer, attention turned to developing systems that took advantage of its memory and processing power.
After a long, slow start U.S. online services eventually grew rapidly. By 1996 more than 13 million American homes subscribed to these services. Customers of consumer-oriented online services generally pay a monthly subscription fee, which includes a limited amount of access time, plus extra fees for additional online time. The fees of business-oriented services tend to be higher, because of the value of the content they provide. The largest consumer-oriented U.S. online systems include America Online, CompuServe, and Prodigy.
Online services have spurred development of other systems delivering similar types of services. For example, the still-experimental "screen phone," a telephone with a small display screen, offers many of the same messaging, directory, banking, and shopping services. The high price of screen phones has stymied deployment of these systems, but their promoters believe they will eventually succeed because phones are more "user friendly" than computers. Television's broadband capacity and its ability to display high-quality moving images has encouraged developers to explore interactive TV as the next medium for such systems.
Gary Arlen
Bibliography: Arlen, Gary H., Information and Interactive Services Report (periodical newsletter); Kinkoph, Sherry, The Complete Idiot's Guide to Modems and Online Services (1994); Koch, Tom, The Message Is the Medium (1996); Saunders, L. M., The Evolving Virtual Library (1996).
Top
One of the first distributed WANs was ARPANET, sponsored by the U.S. Department of Defense Advanced Research Projects Agency and a forerunner of today's best-known WAN, the Internet. Financial institutions are common users of WANs: a bank with automatic teller machines (ATMs) in locations across a city connects those machines to a central computer via a WAN.
Top