WWW or W3: see World Wide Web World Wide Web (WWW or W3), collection of globally distributed text and multimedia documents and files and other network services linked in such a way as to create an immense electronic library from which information can be retrieved quickly by intuitive searches.
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World Wide Web (WWW)

or Web

Leading information-exchange service of the Internet. It was created by Tim Berners-Lee and his colleagues at CERN and introduced to the world in 1991. The Web gives users access to a vast array of documents that are connected to each other by means of hypertext or hyperlinks. A hypertext document with its corresponding text and hyperlinks is written in HTML and is assigned an on-line address, or URL. The Web operates within the Internet's basic client-server architecture. Individual HTML files with unique electronic addresses are called Web pages, and a collection of Web pages and related files (such as graphics files, scripted programs, and other resources) sharing a set of similar addresses (see domain name) is called a Web site. The main or introductory page of a Web site is usually called the site's home page. Users may access any page by typing in the appropriate address, search for pages related to a topic of interest by using a search engine, or move quickly between pages by clicking on hyperlinks incorporated into them. Though introduced in 1991, the Web did not become truly popular until the introduction of Mosaic, a browser with a graphical interface, in 1993. Subsequently, browsers produced by Netscape and Microsoft have become predominant.

WWW

(World Wide Web) The common host name for a Web server. The "www-dot" prefix on Web addresses is widely used to provide a recognizable way of identifying a Web site. Computers read Web addresses (URLs) from right to left, so that the WWW is the last component of the address.

WWW Is Optional
Today, the WWW prefix is mostly optional, and it is common to advertise only the domain name such as computerlanguage.com without the WWW. Web sites are typically configured to default to a WWW Web server if only the domain name is used. Try it. Type the name of a Web site into your browser using only the domain name, such as computerlanguage.com. See dub-dub-dub, World Wide Web, DNS and URL.

WWW2, WWW3, etc.
Organizations use WWW2, WWW3 and other similar prefixes as a way of identifying additional Web sites or Web content. This is strictly an arbitrary naming that differentiates their own sites from the ones that use the WWW prefix, which has become a default. The names have no connection to "Internet 2" or other global systems or standards.

WWW - World-Wide Web