Well, it would be all the stuff in U, it would be all the stuff in U that is not in A. One way to think about it, you could think about it as the relative complement of A that is in U, but when you're taking the relative complement of something that is in the universal set, you're really talking about the absolute complement. Or when people just talk about the complement, that's what they're saying. What's the set of all the things in my universe that are not, that are not in A? Now let's make things a little bit more concrete by talking about sets of numbers. Once again, our sets, we could have been talking about sets of TV personalities or sets of animals or whatever it might be, but numbers are a nice, simple thing to deal with. And let's say that our universe, our universe that we care about right over here, is the set of integers.