The World Wide Web (called WWW or W3 in short) is the most popular and promising method of accessing the internet. The main reason for its popularity is the use of a concept called hypertext.

Hypertext is a new way of information storage and retrieval which enables authors to structure information in novel ways. An effectively designed hypertext document can help users rapidly locate the desired type of information from the vast amount of information on the internet.

Hypertext documents enable this by using a series of links. A link can be shown on the screen in multiple ways, such as a labeled button, highlighted text or different color text than normal text if your computer has a color display, or author-defined graphic symbols.

Link is a special type of item in a hypertext document which connects the document to another document that provides more information about the linked item. The latter document can be anywhere on the internet (in the same document in which the linked item is, in the same computer in which the former document is or in another computer which is at the other end of the world). By “connect” we mean that a user simply selects the linked item (using a mouse or key command) and the user almost   immediately sees the other document on his/her computer terminal.

The concept of hypertext can be best illustrated with the help of an example. Let us assume that the screen of your computer terminal has the following hypertext document currently displayed on it. This hypertext document has the following two links, which are shown on the screen as highlighted (bold and underlined) texts:

1.    Center for Development  of Advanced computing (C-DAC) - Let us assume that this link connects the current document  to another document, which gives detailed information about C-DAC and is located on a computer system at C-DAC in Pune, India.

2.    Multimedia systems Research Laboratory (MSRL) of Panasonic - Let us assume that this link connects the current document to another document, which gives detailed information about MSRL of Panasonic, and is located on a computer system at MSRL of Panasonic in Tokyo, Japan.

Now if you use your mouse to click anywhere on the link Multimedia Systems Research Laboratory (MSRL) of Panasonic, within a few seconds you will find yourself  connected to the computer at MSRL of Panasonic in Tokyo. A document containing detailed information about MSRL will be displayed on your computer screen.

Hypertext documents on the internet are known as Web pages. Web pages are created by using a special  language called Hypertext Markup Language(HTML in short).HTML is a subset of the more generalized language called standard Generalized Markup Language (SGML in short), which is a powerful language for linking documents for easier electronic access and manipulation. HTML is becoming a de-facto industrial standard for creating web pages.

The WWW uses the client-server model and an Internet protocol called Hypertext Transport Protocol (HTTP in short) for interaction between the computers on the internet. Any computer on the internet which uses the HTTP protocol is called a Web Server. And any computer which can access that server is called a Web client. The use of the client-server model and the HTTP allows different kinds of computers on the internet to interact with each other. For example, UNIX workstation may be the web server and a windows pc may be the web client, if both of them use the HTTP protocol for transmitting and receiving information.