This article concerns the claim that it is possible to create living organisms, not merely models that represent organisms, simply by programming computers. I ask what sort of things these computer-generated organisms are supposed to be. I consider four possible answers to this question: The organisms are abstract complexes of pure information; they are material objects made of bits of computer hardware; they are physical processes going on inside the computer; and they are denizens of an entire artificial world, different (...) from our own, that the programmer creates. I argue that could not be right, that collapses into, and that would make strong alife either absurd or uninteresting. Thus, "virtual" strong alife amounts to the claim that, by programming a computer, one can literally bring bits of its hardware to life. (shrink)