"The Web" redirects here. For other uses of web, see Web.

The World Wide Web ("WWW" or simply the "Web") is a global, read-write information space. Text documents, images, multimedia and many other items of information, referred to as resources, are identified by short, unique, global identifiers called Uniform Resource Identifiers (URIs) so that each can be found, accessed and cross-referenced in the simplest possible way.

The term is often mistakenly used as a synonym for the Internet itself, but the Web is actually something that is available over the Internet, just like e-mail and many other Internet services.

Basic terms

The World Wide Web is the combination of four basic ideas-

• Hypertext- a format of information which allows one, in a computer environment, to move from one part of a document to another or from one document to another through internal connections among these documents (called "hyperlinks");
• Resource Identifiers- unique identifiers used to locate a particular resource (computer file, document or other resource) on the network;
• The Client-server model of computing- a system in which client software or a client computer makes requests of server software or a server computer that provides the client with resources or services, such as data or files; and
• Markup language- characters or codes embedded in text which indicate structure, semantic meaning, or advice on presentation.

On the World Wide Web, a client program called a web browser retrieves information resources, such as web pages and other computer files, from web servers using their URLs and displays them, typically on a computer monitor. One can then follow hyperlinks in each page to other resources on the World Wide Web whose location is provided by these hyperlinks. It is also possible, for example by filling in and submitting web forms, to post information back to a web server for it to save or process in some way. The act of following hyperlinks is often called "browsing" or "surfing" the Web. Web pages are often arranged in collections of related material called "websites."

The phrase "surfing the Internet" was first popularized in print by Jean Armour Polly, a librarian, in an article called Surfing the INTERNET, published in the Wilson Library Bulletin in June, 1992. Although Polly may have developed the phrase independently, slightly earlier uses of similar terms have been found on the Usenet from 1991 and 1992, and some recollections claim it was also used verbally in the hacker community for a couple years before that. Polly is famous as "NetMom" in the history of the Internet.

For more information on the distinction between the World Wide Web and the Internet itself — as in everyday use the two are sometimes confused — see Dark internet where this is discussed in more detail.

Although the English word worldwide is normally written as one word (without a space or hyphen), the proper name World Wide Web and abbreviation WWW are now well-established even in formal English. The earliest references to the Web called it the WorldWideWeb (an example of computer programmers' fondness for CamelCase) or the World-Wide Web (with a hyphen, this version of the name is the closest to normal English usage).

Ironically, the abbreviation "WWW" is somewhat impractical as it contains three times as many syllables as the full term "World Wide Web", and thus takes longer to say; however it is easier to type

How the Web works

When a viewer wants to access a web page or other resource on the World Wide Web, he normally begins either by typing the URL of the page into his or her web browser, or by following a hypertext link to that page or resource. The first step, behind the scenes, is for the server-name part of the URL to be resolved into an IP address by the global, distributed Internet database known as the Domain name system or DNS.

The next step is for an HTTP request to be sent to the web server at that IP address, for the page required. In the case of a typical web page, the HTML text, graphics and any other files that form a part of the page will be requested and returned to the client (the web browser) in quick succession.

The web browser's job is then to render the page as described by the HTML, CSS and other files received, incorporating the images, links and other resources as necessary. This produces the on-screen 'page' that the viewer sees.

Most web pages will themselves contain hyperlinks to other relevant and informative pages and perhaps to downloads, source documents, definitions and other web resources.

Such a collection of useful, related resources, interconnected via hypertext links, is what has been dubbed a 'web' of information. Making it available on the Internet produced what Tim Berners-Lee first called the World Wide Web in the early 1990s [1] [2].1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Caching

If the user returns to a page fairly soon, it is likely that the data will not be retrieved from the source web server, as above, again. By default, browsers cache all