World Wide Web
The World Wide Web (WWW), or the web, is a repository of information spread all over the world and linked together. The WWW has a unique combination of flexibility, portability and user-friendly features that distinguish it from other services provided by the Internet.
The WWW project was initiated by CERN (European Laboratory for Particle Physics) to create a system to handle distributed resources necessary for scientific research. The WWW today is a distributed client-server service, in which a client using a browser can access a service using a server. However, the service provided is distributed over many locations called websites.
The web consists of many web pages that incorporate text, graphics, sound, animation and other multimedia components. These web pages are connected to one another by hypertext. In a hypertext environment the information is stored using the concept of pointers. WWW uses a concept of HTTP which allows communicating between a web browser and web server. The web pages can be created by using a HTML (Hyper Text Markup Language). This language has some commands which are used to inform the browser about the way of displaying the text, graphics and multimedia files. HTML also has some commands through which we can give links to the web pages.
If we want to get a page from the web, we have to type URL (Uniform Resource Locator) ‘for our desired page, or otherwise we have to click on a link that provides the URL. The URL specifies the internet address of the web server, the directory and name of our desired page. If there is no directory or web page specified, then the web server will provide a default home page.
The WWW today is a distributed client-server service, in which a client using a browser can access a service using a server. Figure 9.1 illustrates how the different web site can communicate with each other.
Figure 9.1: Distributed Services (Different Websites can communicate with Each Other)
Working of a Web:
The Web operates on a client/server model. A web browser acts as the client in the WWW interaction. Using this program, a user sends a request for a web page stored on a web server. The web server locates this web page and sends it back, to the client computer. The web browser then interprets the web page written in the HTML language and then displays it on the client computer’s screen.
Figure 9.2: Interaction between a Web Browser and a Web server