Internet Intranet and Extranets

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The Internet is a worldwide collection of millions of computers and networks of all sizes. The term Internet is derived from the term internetworking, which means connecting networks. Simply put, the Internet is a network of networks. No one actually owns or runs the Internet, and each network is administered and funded locally.

The Internet backbone is a foundation network linked with fiber-optic cables that can support very high bandwidth. It is called a backbone because it supports all the other networks that form the Internet, just as the human backbone is the foundation of the nervous system. The Internet backbone is made up of many interconnected government, academic, commercial, and other high-capacity data routers.

The World Wide Web (the Web) changed the Internet in 1989 by introducing a graphical interface to the largely text-based Internet. The Web was proposed by Tim Berners-Lee at the European Organization for Nuclear Research (CERN), the world’s largest particle physics center. The Web organizes information by using hypermedia, meaning documents that include embedded references to audio, text, images, video, or other documents. Composed of billions of hypermedia documents, the Web constitutes a large portion of the Internet.

The embedded references in hypermedia documents are called hypertext; they consist of links users can click to follow a particular thread. By using hyper-text links, users can access files, applications, and other computers in any order they like (unlike in paper documents) and retrieve information with the click of a but-ton. In essence, hypertext is an approach to data management, in which data is stored in a network of nodes connected by links. Data in these nodes is accessed with an interactive browsing system, meaning the user determines the order in which information is accessed.

Any computer that stores hypermedia documents and makes them available to other computers on the Internet is called a server or Web server, and computers requesting these documents are called clients. A client can be a home computer or a node in an organization’s LAN. The most exciting feature of the Web is that hypermedia documents can be stored anywhere in the world, so users can jump from a site in the United States to a site in Paris, France, in just a few milliseconds.