World Wide Web

The World Wide Web [ ˌ ː ld ˌ wɜ waɪdwɛb ] (short Web or WWW from the English for: " Global Network") is a retrievable via the Internet system of electronic hypertext documents, called Web pages. You are hyperlinked to each other and are transmitted via the HTTP or HTTPS protocol on the Internet. The websites contain information that is usually present in the form of text, which is often illustrated with photographs and graphic elements. Frequently, videos, audio files or pieces of music are embedded in the web pages.

The WWW was developed under further development of known similar concepts in 1989 by Tim Berners -Lee and Robert Cailliau at the European Research CERN. Berners- Lee proposed to the HTTP communication protocol and the page description language HTML. He also programmed the first web browser and the first web server software. He also ran the first Web server in the world on his development machine type NeXTcube. The overall concept was made public in 1991 waiving any patenting or royalty payments at your disposal, which contributed significantly to the current importance.

The WWW is in common parlance often equated to the Internet, although it is younger and is only one of several possible uses of the Internet. Other Internet services like e- mail, IRC and Telnet are not integrated into the WWW. The World Wide Web has led to extensive, often described as revolutionary upheavals in many areas of life, the emergence of new industries, and to a fundamental change of the communication behavior and media usage. It is partially equated along with other Internet services such as e -mail with the invention of the printing press in its cultural significance.

History

Development

The Web was created in 1989 as a project at the research facility CERN, lying near Geneva on Swiss and French territory on which Tim Berners -Lee built a hypertext system. This idea he presented for the first time on March 12, 1989 in the research facility before. The concept was codesigned by the Belgian Robert Cailliau. The original goal of the system was to exchange research results in a simple manner with colleagues. A method for doing this was the " intertwining " of scientific articles - so creating a web. In Berners- Lee's own words:

"The WorldWideWeb (W3 ) is a wide-area hypermedia information retrieval initiative aiming to give universal access to a large universe of documents. "

" The World Wide Web is a large-scale hypermedia initiative to gather information with the aim to allow universal access to a large collection of documents. "

The concept underlying the hypertext comes from earlier developments on how Ted Nelson's Project Xanadu, Vannevar Bush's " memex " machine idea and the music CodeProject.

The World Wide Web is different from former hypertext systems ( note code used, for example, a simple and readable syntax and semantic descriptors ). The WWW requires only unidirectional links rather than bidirectional, which makes it possible to put a link to a resource without their owners having to intervene. In addition, unlike other protocols such as HyperCard or Gopher, builds the World Wide Web on an empty protocol, which made possible the development of servers and clients without restrictions imposed by licenses. Tim Berners -Lee made the World Wide Web project on 6 August 1991 with a contribution to the newsgroup alt.hypertext publicly and globally available.

The first web viewer that was more of a browser - editor - hybrid, named Berners- Lee simply " WorldWideWeb ". He had written it in the fall of 1990 on a NeXT computer. Later he called it - to avoid confusion with the World Wide Web to avoid (with spaces) - in " Nexus " to. It could then display only text, but later browsers such as Pei Weis Viola (1992 ) added the ability to display graphics added. Marc Andreessen of NCSA published in 1993 a browser called "Mosaic for X", which soon brought the web and all over the Web unprecedented popularity beyond the existing user groups and an explosive growth. Marc Andreessen founded the company " Mosaic Communications Corporation ", later " Netscape Communication ". Meanwhile, modern browsers can also play additional features such as dynamic content, music, animations and videos.

Name

In Berners- Lee's first project draft of March 1989, the Web was still Mesh (English braid). But the name was quickly rejected because it reminds too much of measurement (English disorder ). The following naming attempts Mine of Information (English information mine ) or The Information Mine did not last, as the abbreviations MOI (Fr. I ) had to be self-centered and TIM. In addition, a mine was only partially suitable image, because you can get out of her just a little, the Web, however, provide both information should also be filled with them.

Finally, Berners -Lee settled on the Web and the World Wide Web, although he was warned by colleagues that the tongue twisters in English and French acronym WWW would jeopardize the project's success. Web seemed particularly apt as a picture, as it is a network of nodes ( engl. nodes) called in mathematics, each of which can be associated with each.

Operation

The WWW is based on three core standards:

HTTP as the protocol that the browser can request information from the web server.
HTML as the document description language that specifies how the information is organized and how the documents are linked (hyperlinks).
URLs as unique identifier of a resource that is used in hyperlinks.

The following standards were added later:

Cascading Style Sheets ( CSS) define the appearance of the elements of a web page, with presentation and content are separated.
Hypertext Transfer Protocol Secure (HTTPS ) is a further development of HTTP, in which the SSL protocol is inserted between TCP and HTTP and is completely encoded in the sequence of data transfer.
Document Object Model (DOM) as a programming interface for external programs or scripting languages, web browsers.

Not standardized by the W3 consortium is the most widely used scripting or macro language of web browsers:

JavaScript is a scripting language with instructions for the browser, with the programs ( scripts) can be embedded. This web pages using the Document Object Model (DOM) can be changed dynamically. Scripts are usually small program snippet, but can also take on as a client manager by using the DOM complete control over the display. A developed by Microsoft variant of JavaScript, called JScript. Both languages are similar, but not compatible. This incompatibility of the two languages is a crucial part of the so-called browser war.

The World Wide Web Consortium ( W3C also called ), which is still managed by the inventor of the World Wide Web, Tim Berners -Lee, developed the HTML and CSS standards; other standards coming from the Internet Engineering Task Force, the ECMA or manufacturers such as Sun Microsystems.

The WWW was and is supplemented by other technologies. Images were used to illustrate a very early stage; the formats GIF, PNG and JPEG prevail.

In addition, numerous other file types in browsers by browser extensions, so -called plug -ins are displayed. This multimedia content from animations to music and videos or entire applications such as insurance calculator or navigation interfaces can be displayed. Furthermore, Java applets allow the embedding of programs which run on the computer of the WWW user.

Other popular formats are PDF for viewing documents and Flash for interactive content and animations.

Dynamic Websites and Web Applications

With the help of dynamic web pages, the World Wide Web can be used as surface for distributed programs are used: A program no longer starts conventionally locally on the computer, but is a lot of dynamic Web pages that can be viewed and operated through a web browser. It is advantageous here that the programs are no longer distributed on the individual computers and ( decentralized) must be administered there.

Dynamic Web applications run either on the server or directly in the browser.

Running Web Applications on the Web: The content is in scripting languages ( such as PHP or Perl) or compiled applications ( such as JSP, servlets or ASP.NET) Web applications written produced and delivered to the browser.
Dynamic websites on the client: The browser creates or modifies content using JavaScript.
Mixed Design: A mixed design provides AJAX is - here the browser using JavaScript sends a request that is processed by the web server and so dynamically renewed parts of the HTML structure.

The disadvantage is the limited expressive possibilities of Web pages, so that programs in the form of web pages in general can not be so easily operated like conventional programs. A trend that is trying to get both ends meet, are Rich Internet Applications.

At present, it is observed that more and more services that were originally isolated from the WWW and ran as a separate program, offered through the WWW and can be used by a browser:

So Webmail is often used as an email client or WebFTP as an FTP client; Forums replace Usenet and web chats the IRC.

Compatibility and accessibility

Often, browser vendors introduced new opportunities without waiting for standardization. However, all parts of standards such as HTML and CSS are still not Conversely implemented correctly. This leads to incompatibilities between certain websites and some browsers. Especially " excelled " by such incompatibilities had at the beginning of the Internet boom, the company Netscape, the company now mainly Microsoft with its Internet Explorer.

Also, went through the variety of ad-hoc extensions to HTML a key advantage of this language is lost - the separation of content and presentation. Due to this separation, the excellent in HTML content can optimally for the respective output device - whether screen, mobile phone display or voice output (for users with visual impairment ) - be prepared.

The W3C and other initiatives therefore drive the development forward in the direction of XHTML / XML and CSS to recover these advantages of HTML. The progressive efforts to the accessibility of Internet sites to support this trend.

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