So let's say this whole box is a set of all numbers. So that's all the numbers right over there. We have set x. I'll just draw a circle right over here. And I could even draw the elements of set x. So you have 3 and 5 and 12, 3, 5, 12, and 13. And then we can draw a set y. And notice, I drew a little overlapping here because they overlap at 3.