basics of networking

Editor's note: This post is now part of a series, of which the second part can be found here.
As the guy who reviews networking products, I generally receive a couple of e-mails from readers a day, and most of them, in one way or another, are asking about the basics of networking (as in computer to computer, I am not talking about social networks here.)
Don't get me wrong, I appreciate e-mails because, at the very least, it gives me the impression that there are real people out there amid the sea of spam. But I'd rather not keep repeating myself. So instead of saying the same thing over and over again in individual e-mails, I'll talk all about home networking basics, in layman's terms, in this post.