The internet is an excellent example of WAN. The internet was born out of fear in the Pentagon, the US military headquarters, which wanted its researchers all over America to share sophisticated computers. In the days of the Cold War, it asked a military lab, Advanced Research Projects Agency ARPA, to create a large computer network that had no controlling centre. In the event of a nuclear attack on a centrally managed network, the Pentagon argued, all would be lost. Thus was born the ARPANET in 1969.
World Wide Web (invented by Tim Berners Lee), which allows a point and click navigation without the help of formidable computer commands. Then came Marc Anderson who wrote a program, Mosaic, to add colourful pictures, sound and video to the web. The web is the most impressive internet application. It uses a concept called hypertext, displaying text and images in relation to each other on a web page where individual words or pictures act as electronic links to other (related) documents.
A simple mouse click on a word can take the user to that word’s definition, an illustration, or another related web page. The web documents are written in a computer language called hypertext mark up language (HTML) and transferred by a protocol called hypertext transfer protocol (HTTP). The web pages are identified by unique uniform resource locators (URLs).
The web would have been very difficult to operate but for the hypertext concept. Now one simply types the URL of the page one wants to visit. The computer then displays the page which is an HTML documents with texts, pictures, sounds etc. As the user reads the page, certain words can act as hyperlinks pointers to the URL of other web pages with related information.
The domain name which comes after the symbol@, may also include an extension other than .com which stands for commercial business. It may be on educational institution ‘edu’, on organisation ‘org’ or government departments ‘gov’. Domains are classified as non geographics and geographic, countires have fixed domain names: eg. the domain name of the UK is .uk and that of India is .in. There may be sub domains that correspond to organisations such as NASA.
Some browsers display interlaced GIFs as they read them, first they display every eight line, then fourth line, then every second line and then every line. This display method makes people, waiting for the image to load, to quickly figure out what the final image would look like.
Other browsers bring in a rough version of the graphic and gradually refine it. GIFs also support animation. It is possible to piece together numerous GIFs and create a simple movie.