Making the Net Work: Clients and Servers
The key to doing anything on the Net is understanding two little words: "client" and "server." Figure 1.2 illustrates the relationship between clients and servers.
Figure 1.2. From your computer, you use a set of client programs, each of which accesses a different type of server computer on the Net.
Most of the information you will access through the Internet is stored on computers called servers . A server can be any type of computer; what makes it a server is the role it plays: It stores information for use by clients.
A client is a computer ”or, more accurately, a particular computer program ”that knows how to communicate with a particular type of server to use the information stored on that server (or to put information there). For example, when you surf the Web, you use a client program called a Web browser to communicate with a computer where Web pages are stored ”a Web server.
In general, each type of Internet activity involves a different type of client and server: To use the Web, you need a Web client program to communicate with Web servers. To use email, you need an email client program to communicate with email servers.
This client/server business shows what the Internet really is ”just a communications medium, a virtual wire through which computers communicate. It's the different kinds of clients and servers ”not the Net itself ”that enable you to perform various activities. And because new kinds of clients and servers can be invented, new types of activities can be added to the Internet at any time.