B is subset of A. Every element in B is a member of A. Now we can go even further. We can say that B is a strict subset of A, because B is a subset of A, but it does not equal A, which means that there are things in A that are not in B. So we could even go further. And we could say that B is a strict, or sometimes said, a proper subset of A. And the way you do that is, essentially, you can almost imagine that this is kind of a less than or equal sign.