THE BATTLESPACE C yberspace. It sounds like another dimension, perhaps with green lighting and columns of numbers and symbols flashing in midair, as in the movie The Matrix. Cyberspace is actually much more mundane. It's the laptop you or your kid carries to school, the desktop computer at work. It's a drab windowless building downtown and a pipe under the street. It's everywhere, everywhere there's a computer, or a processor, or a cable connecting to one. . And now it's a war zone, where many of the decisive battles in the twenty-first century will play out. To understand why, we need to answer some prior questions, like: What is cyberspace? How does it work? How can militaries fight in it? I 1 1I i I