Internet applications, such as the Web, are based on the concept of client/server architecture. In a client/server architecture, some application programs act as information providers (servers), while other application programs act as information receivers (clients). The client/server architecture is not one-to-one. That is, a single client can access many different servers, and a single server can be accessed by a number of different clients. Usually, a user runs a client application, such as a Web browser, that contacts one server at a time to obtain information. Because it only needs to access one server at a time, client software can run on almost any computer, including small handheld devices such as personal organizers and cellular telephones (these devices are sometimes called Web appliances). To supply information to others, a computer must run a server application. Although server software can run on any computer, most companies choose large, powerful computers to run server software because the company expects many clients to be in contact with its server at any given time. A faster computer enables the server program to return information with less delay.
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