No computer exists in isolation today. Computers that scientists use in Antarctica to plot temperature trends under the ozone layer hole communicate via satellite to large data banks in North America. TV commercials show a guy driving into the mountains, hiking onto a scenic peak overlooking a vast golden canyon, and connecting his cellular phone to his laptop computer and checking up on his stock portfolio. Moms and Dads send email to their newly liberated children away at college their first year.

However, the technology that makes it possible for computers to "talk" to each other is vast and intricate, depending upon a bewildering variety of standards, protocols and software packages. We can only get a tiny feel for this labyrinthine world in this chapter, for indeed whole courses are devoted to networking.