There are three parts to an Internet connection:
The connection linking them
This configuration is called the client/server model.
In the client/server model, one program requests a service from another program.
The client makes a request
; the server answers the request with a service
The client and server communicate with each other by both physical (hardware) and logical (software) links.
A client consists of:
A desktop computer (hardware)
A program (software) that requests information from the server
The program usually resides on a personal computer.
An example of such a program is a Web browser. When you want to see a particular Web site, the browser handles your request.
Typically a server is a remote device shared by many users. A server can be:
A machine that stores a particular resource you want to use, such as a database or Web pages
A machine that performs specific functions such as sending and receiving e-mail
Servers are available commercially from companies including Sun Microsystems, Sequent, IBM, Unisys, Dell, Compaq, and NCR.
The figure below illustrates the relation between a client and server connected through local and regional Internet Service Providers (ISPs).
In the next lesson, you will learn about the hardware and software you need to access the Internet.