Chapter 1. Introduction

Today people use computers to make phone calls, to watch TV, to send instant messages to their friends, to play games with other people, and to buy almost anything you can think of—from songs to SUVs. The ability for programs to communicate over the Internet makes all this possible. It’s hard to say how many individual computers are now reachable over the Internet, but we can safely say that it is growing rapidly; it won’t be long before the number is in the billions. Moreover, new applications are being developed every day. With the push for ever increasing bandwidth and access, the impact of the Internet will continue to grow for the foreseeable future.

How does a program communicate with another program over a network? The goal of this book is to start you on the road to understanding the answer to that question, in the context of the Java programming language. The Java language was designed from the start for use over the Internet. It provides many useful abstractions for implementing programs that communicate via the application programming interface (API) known as sockets.