World Wide Web


The World Wide Web is an information system that enables content sharing over the Internet using a graphical user interface. It facilitates access to documents and other web resources according to specific rules of the Hypertext Transfer Protocol.
The Web was invented by English computer scientist Tim Berners-Lee while at CERN in 1989 and opened to the public in 1993. It was conceived as a "universal linked information system". Documents and other media content are made available to the network through web servers and can be accessed by programs such as web browsers. Servers and resources on the World Wide Web are identified and located through a character string called uniform resource locator.
The original and still very common document type is a web page formatted in Hypertext Markup Language. This markup language supports plain text, images, embedded video and audio contents, and scripts that implement complex user interaction. The HTML language also supports hyperlinks, which provide immediate access to other web resources. Web navigation, or web surfing, is the common practice of following such hyperlinks across multiple websites. Web applications are web pages that function as application software. The information on the Web is transferred across the Internet using HTTP. Multiple web resources with a common theme and usually a common domain name make up a website. A single web server may provide multiple websites, while some websites, especially the most popular ones, may be provided by multiple servers. Website content is provided by a myriad of companies, organisations, government agencies, and individual users; and comprises an enormous amount of educational, entertainment, commercial, and government information.
The World Wide Web has become the world's dominant information systems platform. It is the primary tool that billions of people worldwide use to interact with the Internet.

History

The Web was invented by English computer scientist Tim Berners-Lee while working at CERN. He was motivated by the problem of storing, updating, and finding documents and data files in that large and constantly changing organisation, as well as distributing them to collaborators outside CERN. In his design, Berners-Lee dismissed the common tree structure approach, used for instance in the existing CERNDOC documentation system and in the Unix filesystem, as well as approaches that relied on tagging files with keywords, as in the VAX/NOTES system. Instead, he adopted concepts he had put into practice with his private ENQUIRE system, built at CERN. When he became aware of Ted Nelson's hypertext model, in which documents can be linked in unconstrained ways through hyperlinks associated with "hot spots" embedded in the text, it helped to confirm the validity of his concept.
The model was later popularised by Apple's HyperCard system. Unlike Hypercard, Berners-Lee's new system from the outset was meant to support links between multiple databases on independent computers, and to allow simultaneous access by many users from any computer on the Internet. He also specified that the system should eventually handle other media besides text, such as graphics, speech, and video. Links could refer to mutable data files, or even fire up programs on their server computer. He also conceived "gateways" that would allow access through the new system to documents organised in other ways. Moreover, he insisted that the system should be decentralised, without any central control or coordination over the creation of links.
Berners-Lee submitted a proposal to CERN in May 1989, without giving the system a name. He got a working system implemented by the end of 1990, including a browser called WorldWideWeb and an HTTP server running at CERN. As part of that development, he defined the first version of the HTTP protocol, the basic URL syntax, and implicitly made HTML the primary document format. The technology was released outside CERN to other research institutions starting in January 1991, and then to the whole Internet on 23 August 1991. The Web was a success at CERN and began to spread to other scientific and academic institutions. Within the next two years, there were 50 websites created.
CERN made the Web protocol and code available royalty free on 30 April 1993, enabling its widespread use. After the NCSA released the Mosaic web browser later that year, the Web's popularity grew rapidly as thousands of websites sprang up in less than a year. Mosaic was a graphical browser that could display inline images and submit forms that were processed by the HTTPd server. Marc Andreessen and Jim Clark founded Netscape the following year and released the Navigator browser, which introduced Java and JavaScript to the Web. It quickly became the dominant browser. Netscape became a public company in 1995, which triggered a frenzy for the Web and started the dot-com bubble. Microsoft responded by developing its own browser, Internet Explorer, starting the browser wars. By bundling it with Windows, it became the dominant browser for 14 years.
Berners-Lee founded the World Wide Web Consortium which created XML in 1996 and recommended replacing HTML with stricter XHTML. In the meantime, developers began exploiting an IE feature called XMLHttpRequest to make Ajax applications and launched the Web 2.0 revolution. Mozilla, Opera, and Apple rejected XHTML and created the WHATWG which developed HTML5. In 2009, the W3C conceded and abandoned XHTML. In 2019, it ceded control of the HTML specification to the WHATWG.
The World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet.

Competition with Gopher

was run by the University of Minnesota and the alternative to the World Wide Web.
  • In February 1993, the University of Minnesota announced that it would charge licensing fees for the use of its implementation of the Gopher server. Users became concerned that fees might also be charged for independent implementations. Gopher expansion stagnated, to the advantage of the World Wide Web which released the WWW into the public domain in April 1993, to which CERN maintained. In September 2000, the University of Minnesota re-licensed its Gopher software under the GNU General Public License.
  • Gopher client functionality was quickly duplicated by the early Mosaic web browser, which subsumed its protocol.
  • Gopher has a more rigid structure than the free-form HyperText Markup Language of the Web. Every Gopher document has a defined format and type, and the typical user navigates through a single server-defined menu system to get to a particular document. This can be quite different from the way a user finds documents on the Web.
  • Failure to follow the open systems model and bad publicity in comparison to the World Wide Web.

    Nomenclature

Tim Berners-Lee states that World Wide Web is officially spelled as three separate words, each capitalised, with no intervening hyphens. Use of the www prefix has been declining, especially when web applications sought to brand their domain names and make them easily pronounceable. As the mobile web grew in popularity, services like Gmail.com, Outlook.com, Myspace.com, Facebook.com and Twitter.com are most often mentioned without adding "www." to the domain.
In English, www is usually read as double-u double-u double-u. Some users pronounce it dub-dub-dub, particularly in New Zealand. Stephen Fry, in his "Podgrams" series of podcasts, pronounces it wuh wuh wuh. The English writer Douglas Adams once quipped in The Independent on Sunday : "The World Wide Web is the only thing I know of whose shortened form takes three times longer to say than what it's short for".

Function

The terms Internet and World Wide Web are often used without much distinction. However, the two terms do not mean the same thing. The Internet is a global system of computer networks interconnected through telecommunications and optical networking. In contrast, the World Wide Web is a global collection of documents and other resources, linked by hyperlinks and URIs. Web resources are accessed using HTTP or HTTPS, which are application-level Internet protocols that use the Internet transport protocols.
Viewing a web page on the World Wide Web normally begins either by typing the URL of the page into a web browser or by following a hyperlink to that page or resource. The web browser then initiates a series of background communication messages to fetch and display the requested page. In the 1990s, using a browser to view web pages—and to move from one web page to another through hyperlinks—came to be known as 'browsing,' 'web surfing', or 'navigating the Web'. Early studies of this new behaviour investigated user patterns in using web browsers. One study, for example, found five user patterns: exploratory surfing, window surfing, evolved surfing, bounded navigation, and targeted navigation.
The following example demonstrates the functioning of a web browser when accessing a page at the URL. The browser resolves the server name of the URL into an Internet Protocol address using the globally distributed Domain Name System. This lookup returns an IP address such as 203.0.113.4 or 2001:db8:2e::7334. The browser then requests the resource by sending an HTTP request across the Internet to the computer at that address. It requests service from a specific TCP port number that is well known for the HTTP service, so that the receiving host can distinguish an HTTP request from other network protocols it may be servicing. HTTP normally uses port number 80 and, for HTTPS, it normally uses port number 443. The content of the HTTP request can be as simple as two lines of text:

GET /home.html HTTP/1.1
Host: example.org

The computer receiving the HTTP request delivers it to the web server software listening for requests on port 80. If the web server can fulfil the request, it sends an HTTP response back to the browser indicating success:

HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8

Followed by the content of the requested page. Hypertext Markup Language for a basic web page might look like this:



Example.org – The World Wide Web


The World Wide Web, abbreviated as WWW and commonly known...





The web browser parses the HTML and interprets the markup that surrounds the words to format the text on the screen. Many web pages use HTML to reference the URLs of other resources such as images, other embedded media, scripts that affect page behaviour, and Cascading Style Sheets that affect page layout. The browser makes additional HTTP requests to the web server for these other Internet media types. As it receives its content from the web server, the browser progressively renders the page onto the screen as specified by its HTML and these additional resources.