Everything about The Web totally explained
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"The World Wide Web" and "WWW" redirect here. For other uses, see Web and WWW (disambiguation). » "Web surfing" redirects here. For the Web browser, see WorldWideWeb.
The
World Wide Web (commonly shortened to
the Web) is a system of interlinked
hypertext documents accessed via the
Internet. With a
Web browser, a user views
Web pages that may contain
text,
images,
videos, and other
multimedia and navigates between them using
hyperlinks. The World Wide Web was created in 1989 by
Sir Tim Berners-Lee, working at
CERN in
Geneva,
Switzerland and released in 1992. Since then, Berners-Lee has played an active role in guiding the development of Web standards (such as the
markup languages in which Web pages are composed), and in recent years has advocated his vision of a
Semantic Web.
How the Web works
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 communication messages, behind the scenes, in order to fetch and display it.
First, the server-name portion of the URL is resolved into an
IP address using the global, distributed
Internet database known as the
domain name system, or DNS. This IP address is necessary to contact and send data
packets to the
Web server.
The browser then requests the resource by sending an
HTTP request to the Web server at that particular address. In the case of a typical Web page, the
HTML text of the page is requested first and
parsed immediately by the Web browser, which will then make additional requests for images and any other files that form a part of the page. Statistics measuring a website's popularity are usually based on the number of '
page views' or associated server '
hits', or file requests, which take place.
Having received the required files from the Web server, the browser then
renders the page onto the screen as specified by its HTML,
CSS, and other Web languages. Any images and other resources are incorporated to produce the on-screen Web page that the user sees.
Most Web pages will themselves contain
hyperlinks to other related 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 was dubbed a "web" of information. Making it available on the Internet created what
Tim Berners-Lee first called the
WorldWideWeb (a term written in
CamelCase, subsequently discarded) in
1990.
History
The underlying ideas of the Web can be traced as far back as 1980, when, at
CERN in
Switzerland,
Tim Berners-Lee built
ENQUIRE (referring to
Enquire Within Upon Everything, a book he recalled from his youth). While it was rather different from the system in use today, it contained many of the same core ideas (and even some of the ideas of Berners-Lee's next project after the World Wide Web, the
Semantic Web).
In March 1989, Tim Berners-Lee wrote a proposal, which referenced ENQUIRE and described a more elaborate information management system. With help from
Robert Cailliau, he published a more formal proposal for the World Wide Web on
November 12,
1990. The role model was provided by EBT's (Electronic Book Technology, a spin-off from the
Institute for Research in Information and Scholarship at Brown University) Dynatext SGML reader that CERN had licensed. The
Dynatext system was considered, however technically advanced (a key player in the extension of SGML ISO 8879:1986 to Hypermedia within
HyTime), too expensive and with an inappropriate licensing policy for general HEP (High Energy Physics) community use: a fee for each document and each time a document was charged.
A
NeXTcube was used by Berners-Lee as the world's first
Web server and also to write the first
Web browser,
WorldWideWeb, in 1990. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the
first Web browser (which was a Web editor as well), the first Web server, and the first Web pages which described the project itself.
On
August 6,
1991, he posted a short summary of the World Wide Web project on the
alt.hypertext newsgroup. This date also marked the debut of the Web as a publicly available service on the Internet.
First server outside of Europe was created at
SLAC in December 1991 .
The crucial underlying concept of
hypertext originated with older projects from the 1960s, such as the Hypertext Editing System (HES) at Brown University--- among others
Ted Nelson and
Andries van Dam---
Ted Nelson's
Project Xanadu and
Douglas Engelbart's
oN-Line System (NLS). Both Nelson and Engelbart were in turn inspired by
Vannevar Bush's
microfilm-based "
memex," which was described in the 1945 essay "
As We May Think".
Berners-Lee's breakthrough was to marry hypertext to the Internet. In his book
Weaving The Web, he explains that he'd repeatedly suggested that a marriage between the two technologies was possible to members of
both technical communities, but when no one took up his invitation, he finally tackled the project himself. In the process, he developed a system of globally unique identifiers for resources on the Web and elsewhere: the
Uniform Resource Identifier.
The World Wide Web had a number of differences from other hypertext systems that were then available. The Web required only unidirectional links rather than bidirectional ones. This made it possible for someone to link to another resource without action by the owner of that resource. It also significantly reduced the difficulty of implementing Web servers and browsers (in comparison to earlier systems), but in turn presented the chronic problem of
link rot. Unlike predecessors such as
HyperCard, the World Wide Web was non-proprietary, making it possible to develop servers and clients independently and to add extensions without licensing restrictions.
On
April 30,
1993,
CERN announced that the World Wide Web would be free to anyone, with no fees due. Coming two months after the announcement that the
Gopher protocol was no longer free to use, this produced a rapid shift away from Gopher and towards the Web. An early popular Web browser was
ViolaWWW, which was based upon
HyperCard.
Scholars generally agree, however, that the
turning point for the World Wide Web began with the introduction of the
Mosaic Web browser in 1993, a graphical browser developed by a team at the
National Center for Supercomputing Applications at the
University of Illinois at Urbana-Champaign (NCSA-UIUC), led by
Marc Andreessen. Funding for Mosaic came from the
High-Performance Computing and Communications Initiative, a funding program initiated by then-Senator
Al Gore's
High Performance Computing and Communication Act of 1991, also known as the
Gore Bill. (See
Al Gore's contributions to the Internet and technology for more information.) Prior to the release of Mosaic, graphics were not commonly mixed with text in Web pages, and its popularity was less than older protocols in use over the Internet, such as
Gopher and
Wide Area Information Servers (WAIS). Mosaic's graphical user interface allowed the Web to become, by far, the most popular Internet protocol.
The World Wide Web Consortium (W3C) was founded by Tim Berners-Lee after he left the European Organization for Nuclear Research (
CERN) in October, 1994. It was founded at the
Massachusetts Institute of Technology Laboratory for Computer Science (MIT/LCS) with support from the
Defense Advanced Research Projects Agency (DARPA) -- which had pioneered the
Internet -- and the
European Commission.
History in literature
The concept of a home-based global information system goes back at least as far as
Isaac Asimov's short story "Anniversary" (
Amazing Stories, March
1959), in which the characters look up information on a
home computer called a "
Multivac outlet" — which was connected by a "planetwide network of circuits" to a mile-long "super-computer" somewhere in the bowels of the Earth. One character is thinking of installing a Multivac, Jr. model for his kids.
The story was set in the far distant future when commercial space travel was commonplace, and yet the machine "prints the answer on a slip of tape" that comes out a slot — there's no video display — and the owner of the home computer says that he doesn't spend the kind of money to get a Multivac outlet that talks.
Standards
Many formal standards and other technical specifications define the operation of different aspects of the World Wide Web, the Internet, and computer information exchange. Many of the documents are the work of the
World Wide Web Consortium (W3C), headed by Berners-Lee, but some are produced by the
Internet Engineering Task Force (IETF) and other organizations.
Usually, when Web standards are discussed, the following publications are seen as foundational:
Additional publications provide definitions of other essential technologies for the World Wide Web, including, but not limited to, the following:
Uniform Resource Identifier (URI), which is a universal system for referencing resources on the Internet, such as hypertext documents and images. URIs, often called URLs, are defined by the IETF's RFC 3986 / STD 66: Uniform Resource Identifier (URI): Generic Syntax, as well as its predecessors and numerous URI scheme-defining RFCs;
HyperText Transfer Protocol (HTTP), especially as defined by RFC 2616: HTTP/1.1 and RFC 2617: HTTP Authentication, which specify how the browser and server authenticate each other.
Java and JavaScript
A significant advance in Web technology was Sun Microsystems' Java platform. It enables Web pages to embed small programs (called applets) directly into the view. These applets run on the end-user's computer, providing a richer user interface than simple Web pages. Java client-side applets never gained the popularity that Sun had hoped for a variety of reasons, including lack of integration with other content (applets were confined to small boxes within the rendered page) and the fact that many computers at the time were supplied to end users without a suitably installed Java Virtual Machine, and so required a download by the user before applets would appear. Adobe Flash now performs many of the functions that were originally envisioned for Java applets, including the playing of video content, animation, and some rich UI features. Java itself has become more widely used as a platform and language for server-side and other programming.
JavaScript, on the other hand, is a scripting language that was initially developed for use within Web pages. The standardized version is ECMAScript. While its name is similar to Java, JavaScript was developed by Netscape and it has almost nothing to do with Java, although, like Java, its syntax is derived from the C programming language. In conjunction with a Web page's Document Object Model, JavaScript has become a much more powerful technology than its creators originally envisioned. The manipulation of a page's Document Object Model after the page is delivered to the client has been called Dynamic HTML (DHTML), to emphasize a shift away from static HTML displays.
In simple cases, all the optional information and actions available on a JavaScript-enhanced Web page will have been downloaded when the page was first delivered. Ajax ("Asynchronous JavaScript And XML") is a group of inter-related web development techniques used for creating interactive web applications that provide a method whereby parts within a Web page may be updated, using new information obtained over the network at a later time in response to user actions. This allows the page to be more responsive, interactive and interesting, without the user having to wait for whole-page reloads. Ajax is seen as an important aspect of what is being called Web 2.0. Examples of Ajax techniques currently in use can be seen in Gmail, Google Maps, and other dynamic Web applications.
Publishing Web pages
Web page production is available to individuals outside the mass media. In order to publish a Web page, one doesn't have to go through a publisher or other media institution, and potential readers could be found in all corners of the globe.
Many different kinds of information are available on the Web, and for those who wish to know other societies, cultures, and peoples, it has become easier.
The increased opportunity to publish materials is observable in the countless personal and social networking pages, as well as sites by families, small shops, etc., facilitated by the emergence of free Web hosting services.
Statistics
According to a 2001 study, there were more than 550 billion documents on the Web, mostly in the "invisible Web", or deep Web. A 2002 survey of 2,024 million Web pages determined that by far the most Web content was in English: 56.4%; next were pages in German (7.7%), French (5.6%), and Japanese (4.9%). A more recent study, which used Web searches in 75 different languages to sample the Web, determined that there were over 11.5 billion Web pages in the publicly indexable Web as of the end of January 2005. As of 2008, the indexed web contains at least 45 billion pages.
Over 100.1 million websites operated as of March 2008. Of these 74% were commercial or other sites operating in the .com generic top-level domain. About 26% of websites operated outside .com addresses. Avoiding infection requires updates to the user's operating system, browser and browser add-ons.
