Encyclopedia of Computer Science and Technology

518 World Wide WebBy the beginning of the 1990s, the Internet had becomewell established as a means of communication betweenrelatively advanced computer users, particularly scientists,engineers, and computer science students—primarily usingUNIX-based systems (see unix). A number of services usedthe Internet protocol (see tcp/ip) to carry messages or data.These included e-mail, file transfer protocol (see ftp) andnewsgroups (see netnews and newsgroups). A Wide AreaInformation Service (WAIS) even provided a protocol forusers to retrieve information from databases on remotehosts. Another interesting service, Gopher, was developedat the University of Minnesota in 1991. It used a system ofnested menus to organize documents at host sites so theycould be browsed and retrieved by remote users.Gopher was quite popular for a few years, but it wouldsoon be overshadowed by a rather different kind of networkedinformation service. A physicist/programmer (seeBerners-Lee, Tim) working at CERN, the European particlephysics laboratory in Switzerland had devised in 1989a system that he eventually called the World Wide Web(sometimes called WWW or W3). By 1990, he was runninga prototype system and demonstrating it for CERNresearchers and a few outside participants.Using the WebThe Web consists essentially of three parts. Berners-Leedevised a markup language: that is, a system for indicatingdocument elements (such as headers), text characteristics,and so on (see html). Any document could be linkedto another (see hypertext and hypermedia) by specifyingthat document’s unique address (called a UniformResource Locator or URL) in a request. Berners-Lee definedthe HyperText Transport Protocol, or HTTP, to handle thedetails needed to retrieve documents. (Although HTTP ismost often used to retrieve HTML-formatted Web documents,it can also be used to specify documents using otherprotocols, such as ftp, news, or Gopher.)A program (see Web server) responds to requests fordocuments sent over the network (usually the Internet, thatis, TCP/IP). The requests are issued by a client program asa result of the user clicking on highlighted links or buttonsor specifying addresses (see Web browser). The browserin turn interprets the HTML codes on the page to display itcorrectly on the user’s screen.At first the Web had only text documents. However,thanks to Berners-Lee’s flexible design (see client-servercomputing) new, improved Web browsers could be createdand used with the Web as long as they followed therules for HTTP. The most successful of these new browserswas Mosaic, created by Marc Andreesen at the NationalCenter for Supercomputing Applications. NCSA Mosaic wasavailable for free download and could run on Windows,Macintosh, and UNIX-based systems. Mosaic not only dispensedwith the text commands used by most of the firstbrowsers, it also had the ability to display graphics andplay sound files. With Mosaic the text-only hypertext of theearly Web rapidly became a richer hypermedia experience.And thanks to the ability of browsers to accept modules tohandle new kinds of files (see plug-in), the Web could alsoaccommodate real-time sound and video transmissions (seestreaming).In 1994, Andreessen left NCSA and co-founded a companycalled Netscape Communications, which improvedand commercialized Mosaic. Microsoft soon entered witha competitor, Internet Explorer; today these two browsersdominate the market with Microsoft having taken thelead. Together with relatively low-cost Internet access(see modem and internet service provider) these userfriendlyWeb browsers brought the Web (and thus theunderlying Internet) to the masses. Schools and librariesbegan to offer Web access while workplaces began to useinternal webs to organize information and organize operations.Meanwhile, companies such as the on-line booksellerAmazon.com demonstrated new ways to deliver traditionalproducts, while the on-line auction site eBay took advantageof the unique characteristics of the on-line medium toredefine the auction.The burgeoning Web was soon offering millions ofpages, especially as entrepreneurs began to find additionalbusiness opportunities in the new medium (see e-commerce).Two services emerged to help Web users makesense of the flood of information. Today users can searchfor words or phrases (see search engine) or browsethrough structured topical listings (see portal). Estimatesfrom various sources suggest that as of 2007 approximately1.2 billion people worldwide access the Web, with usageincreasing most rapidly in the emerging industrial superpowersof India and China.Impact and TrendsThe Web is rapidly emerging as an important news medium(see journalism and the computer industry). Themedium combines the ability of broadcasting to reach manypeople from one point with the ability to customize contentto each person’s preferences. Traditional broadcastingand publishing are constrained by limited resources andthe need for profitability, and thus the range and diversityof views made available tend to be limited. With the Web,anyone with a PC and a connection to a service providercan put up a Web site and say just about anything. Millionsof people now display aspects of their lives and interests ontheir personal Web pages (see blogs and blogging). TheWeb has also provided a fertile medium for the creation ofonline communities (see social networking and virtualcommunity) while contributing to significant issues (seeprivacy in the digital age).As the new century continues, the Web is proving itselfto be truly worldwide, resilient, and adaptable to many newcommunications and media technologies (see digital convergence).Nevertheless, the Web faces legal and politicalchallenges (see censorship and the Internet, and intellectualproperty and computing) as well as technicalchallenges (see semantic Web and Web 2.0).Further ReadingBerners-Lee, Tim. Weaving the Web: The Original Design and UltimateDestiny of the World Wide Web. New York: Harperbusiness,2000.