For those who didn't buy the first edition, welcome aboard. For those who did buy the first edition, welcome back, and thanks for making the second edition possible. For those who bought the first edition and are standing in the book store wondering whether to buy the second, what's in it for you? Well, for one thing, it's smaller. (No, no! Don't leave!) I tried to make the first edition a kind of master reference for antiviral protection. That meant I included a lot of stuff that I thought might possibly be helpful, even if I had some doubts about it. This time I've tried to be a little more selective. I've added a little more material to Chapter 4 (Computer Opera tions and Viral Operations) dealing with the question of computer vi ruses infecting data files and the new "macro" viruses. I've added two new sections to Chapter 7 (The Virus and Society). One looks at the increasing problem of false alarms while the other looks at the ethics of virus writing and exchange.