World Wide Web

The World Wide Web (abbreviated as WWW or W3,2 and frequently accepted as the Web) is a arrangement of interlinked hypertext abstracts accessed via the Internet. With a web browser, one can appearance web pages that may accommodate text, images, videos, and added multimedia, and cross amid them via hyperlinks.

Using concepts from his beforehand hypertext systems like ENQUIRE, British architect and computer scientist Sir Tim Berners-Lee, now Director of the World Wide Web Consortium (W3C), wrote a angle in March 1989 for what would eventually become the World Wide Web.1 At CERN, a European analysis alignment abreast Geneva anchored on Swiss and French soil,3 Berners-Lee and Belgian computer scientist Robert Cailliau proposed in 1990 to use hypertext "... to articulation and admission advice of assorted kinds as a web of nodes in which the user can browse at will",4 and they about alien the activity in December.5

Function

The agreement Internet and World Wide Web are generally acclimated in accustomed accent after abundant distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a all-around arrangement of commutual computer networks. In contrast, the Web is one of the casework that runs on the Internet. It is a accumulating of argument abstracts and added resources, affiliated by hyperlinks and URLs, usually accessed by web browsers from web servers. In short, the Web can be anticipation of as an appliance "running" on the Internet.24

Viewing a web folio on the World Wide Web commonly begins either by accounting the URL of the folio into a web browser or by afterward a hyperlink to that folio or resource. The web browser again initiates a alternation of advice messages, abaft the scenes, in adjustment to back and affectation it. As an example, accede accessing a folio with the URL http://example.org/wiki/World_Wide_Web .

First, the browser resolves the server-name allocation of the URL (example.org) into an Internet Agreement abode appliance the globally broadcast database accepted as the Domain Name Arrangement (DNS); this lookup allotment an IP abode such as 208.80.152.2. The browser again requests the ability by sending an HTTP appeal beyond the Internet to the computer at that accurate address. It makes the appeal to a accurate appliance anchorage in the basal Internet Agreement Suite so that the computer accepting the appeal can analyze an HTTP appeal from added arrangement protocols it may be application such as e-mail delivery; the HTTP agreement commonly uses anchorage 80. The agreeable of the HTTP appeal can be as simple as the two curve of text

Linking

Most web pages accommodate hyperlinks to added accompanying pages and conceivably to downloadable files, antecedent documents, definitions and added web resources. In the basal HTML, a hyperlink looks like

Such a accumulating of useful, accompanying resources, commutual via hypertext links is dubbed a web of information. Publication on the Internet created what Tim Berners-Lee aboriginal alleged the WorldWideWeb (in its aboriginal CamelCase, which was after discarded) in November 1990.4

The hyperlink anatomy of the WWW is declared by the webgraph: the nodes of the webgraph accord to the web pages (or URLs) the directed edges amid them to the hyperlinks.

Over time, abounding web assets acicular to by hyperlinks disappear, relocate, or are replaced with altered content. This makes hyperlinks obsolete, a abnormality referred to in some circles as articulation rot and the hyperlinks afflicted by it are generally alleged asleep links. The brief attributes of the Web has prompted abounding efforts to annal web sites. The Internet Archive, alive back 1996, is one of the best-known efforts.

Dynamic updates of web pages

JavaScript is a scripting accent that was initially developed in 1995 by Brendan Eich, again of Netscape, for use aural web pages.25 The connected adaptation is ECMAScript.25 To affected some of the limitations of the page-by-page archetypal declared above, some web applications additionally use Ajax (asynchronous JavaScript and XML). JavaScript is delivered with the folio that can accomplish added HTTP requests to the server, either in acknowledgment to user accomplishments such as mouse-clicks or based on accomplished time. The server's responses are acclimated to adapt the accepted folio rather than creating a fresh folio with anniversary response. Thus, the server charge accommodate alone limited, incremental information. Since assorted Ajax requests can be handled at the aforementioned time, users can collaborate with a folio alike while abstracts is actuality retrieved. Some web applications consistently poll the server to ask whether fresh advice is available.26

WWW prefix

Many area names acclimated for the World Wide Web activate with www because of the abiding convenance of allotment Internet hosts (servers) according to the casework they provide. The hostname for a web server is generally www, in the aforementioned way that it may be ftp for an FTP server, and account or nntp for a USENET account server. These host names arise as Area Name System (DNS) subdomain names, as in www.example.com. The use of 'www' as a subdomain name is not appropriate by any abstruse or action standard; indeed, the aboriginal anytime web server was alleged nxoc01.cern.ch,27 and abounding web sites abide after it. According to Paolo Palazzi,28 who formed at CERN forth with Tim Berners-Lee, the accepted use of 'www' subdomain was accidental; the World Wide Web activity folio was advised to be appear at www.cern.ch while info.cern.ch was advised to be the CERN home page, about the dns annal were never switched, and the convenance of prepending 'www' to an institution's website area name was after copied. Abounding accustomed websites still use 'www', or they ad-lib added subdomain names such as 'www2', 'secure', etc. Abounding such web servers are set up such that both the area basis (e.g., example.com) and the www subdomain (e.g., www.example.com) accredit to the aforementioned site; others crave one anatomy or the other, or they may map to altered web sites.

The use of a subdomain name is advantageous for amount acclimation admission web cartage by creating a CNAME almanac that credibility to a array of web servers. Since, currently, alone a subdomain can be acclimated in a CNAME, the aforementioned aftereffect cannot be accomplished by application the bald area root.

When a user submits an abridged area name to a web browser in its abode bar ascribe field, some web browsers automatically try abacus the prefix "www" to the alpha of it and possibly ".com", ".org" and ".net" at the end, depending on what ability be missing. For example, entering 'microsoft' may be adapted to http://www.microsoft.com/ and 'openoffice' to http://www.openoffice.org. This affection started actualization in aboriginal versions of Mozilla Firefox, back it still had the alive appellation 'Firebird' in aboriginal 2003, from an beforehand convenance in browsers such as Lynx.29 It is appear that Microsoft was accepted a US apparent for the aforementioned abstraction in 2008, but alone for adaptable devices.30

In English, www is arresting by alone pronouncing the name of characters (double-u double-u double-u) or by adage the byword "triple double-u". Although some abstruse users accent it dub-dub-dub, this is not boundless (although is frequently acclimated by the accepted accessible in New Zealand). The English biographer Douglas Adams already quipped in The Independent on Sunday (1999): "The World Wide Web is the alone affair I apperceive of whose beneath anatomy takes three times best to say than what it's abbreviate for," with Stephen Fry after pronouncing it in his "Podgrammes" alternation of podcasts as "wuh wuh wuh." In Mandarin Chinese, World Wide Web is frequently translated via a phono-semantic analogous to wàn wéi wǎng (万维网), which satisfies www and actually agency "myriad dimensional net",31 a adaptation that actual appropriately reflects the architecture abstraction and admeasurement of the World Wide Web. Tim Berners-Lee's web-space states that World Wide Web is clearly spelled as three abstracted words, anniversary capitalized, with no amid hyphens.32

Use of the www prefix is crumbling as Web 2.0 web applications seek to cast their area names and accomplish them calmly pronounceable.33 As the adaptable web grows in popularity, casework like Gmail.com, MySpace.com, Facebook.com and Twitter.com are best generally discussed after abacus the www to the area (or the .com)

Specifiers: http and https

The arrangement specifiers (http:// or https://) in URIs accredit to the Hypertext Transfer Agreement and to HTTP Secure, respectively, and so ascertain the advice agreement to be acclimated for the appeal and response. The HTTP agreement is axiological to the operation of the World Wide Web; the added encryption band in HTTPS is capital back arcane advice such as passwords or cyberbanking advice are to be exchanged over the accessible Internet. Web browsers usually prepend the arrangement to URLs too, if omitted.