The Internet is a worldwide system of computer networks - a network of networks in which users at any one computer can get information from any other computer in the Internet. A network is a series of computers interconnected by communication paths. Networks can be characterized as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) depending upon the geographical implementation of the network.Today, the Internet is a public, cooperative, and self-sustaining facility accessible to millions of people worldwide. Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks. Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol).For many Internet users, electronic mail (e-mail) has practically replaced the Postal Service for short written transactions. Electronic mail is the most widely used application on the Net.The most widely used part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the Web"). Its outstanding feature is hypertext, a method of instant cross-referencing. In most Web sites, certain words or phrases appear in text of a different color than the rest; often this text is also underlined. When you select one of these words or phrases, you will be transferred to the site or page that is relevant to this word or phrase. Sometimes there are buttons, images, or portions of images that are "clickable." If you move the pointer over a spot on a Web site and the pointer changes into a hand, this indicates that you can click and be transferred to another site.A browser is an application program that provides a way to look at and interact with all the information on the World Wide Web. Any user who wants to view the web sites on Internet needs to have a browser program. For example Internet Explorer, Netscape Navigator etc. It is a basic tool required to surf Internet. For example if you want to watch movies, Cricket matches etc on Television you need a TV set and a cable connection or Antenna to receive the signals. Similarly for surfing the Internet you need a computer and an Internet connection through some service provider (Normally known as ISP) and browser software like Internet Explorer installed in your computer.Technically, a Web browser is a client program that uses HTTP (Hypertext Transfer Protocol) to make requests of Web servers throughout the Internet on behalf of the browser user.HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP.