1.1 What Is the Internet?

In this website, we'll use the public Internet, a specific computer network, as our principal
vehicle for discussing computer networks and their protocols. But what is the
Internet? There are a couple of ways to answer this question. First, we can describe
the nuts and bolts of the Internet, that is, the basic hardware and software components
that make up the Internet. Second, we can describe the Internet in terms of a networking
infrastructure that provides services to distributed applications. Let's begin
with the nuts-and-bolts description, using Figure 1.1 to illustrate our discussion.