Preliminaries

In this section we will develop a concept map and vocabulary that will serve as a foundation for our discussion throughout this guide. We will first discuss the Client-Server Model; then learn where in the "Programmer's model" of a computer these client and server programs reside. We finally learn how these client-server programs communicate with each other over the Internet using URLs.

By the end of this section you should have a working definition and a concept map interlinking the following terms:

• Client
• Server
• Computer
• Program
• Programmer's Model
• Port
• IP address
• URL
• Internet
• OSI Model
• HTTP
• HTTP request
• HTTP response