What Should People Understand About Computers?

counterexample asks: "It seems to me that there aren't very many good books out there that explain to the layman what is really going on with computers. My mother cannot go to the bookstore and pick up a book that will make her understand the strange language that we IT people speak, or why her computer would be susceptible to a virus. So, I intend to write such a book. I have a fair idea of what should be in it (history of the Internet, how computers talk to each other, what a hard drive does, etc.), but I'm interested to see what you all have to say. What do you wish your users knew? What kind of questions are you so sick of answering because you hear them every week? What does the general public think they understand, but really don't?"