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The Internet

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 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 button. 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. Domain names, such as IBM.com or whitehouse.gov, are unique identifiers of computer or network addresses on the Internet. Each computer or network also has an Internet Protocol (IP) address, which is assigned by the Internet Corporation for Assigned Names and Numbers (ICANN). These numbers are difficult to remember, however, so language-based domain names are used more often to access Web sites. When information is transferred from one network to another, domain names are converted to IP addresses by the Domain Name System (DNS) protocol. Servers using this protocol (called DNS servers) maintain lists of computers’ and Web sites’ addresses and their associated IP addresses. DNS servers translate all domain names into IP addresses. You see domain names used in uniform resource locators (URLs), also called universal resource locators, to identify a Web page. A URL is the address of a document or site on the Internet. There are several methods for connecting to a network, including the Internet. These methods include dial-up and cable modems as well as Digital Subscriber Line (DSL).