Maybe artificial life seems like the subject of science fiction movie. But it's a lot more real than most of us realize: online "life forms" such as computer viruses that are transmitted via email are quite alive, mutating and reproducing independently once sinister programmers create them. Canadian net artist Cheryl Sourkes's "Field Guide to Artificial Life on the Web" clarifies what "boids" and "floys" are...and their wild cousins the computer viruses, of course.