Now let's go the other way around. Let's think about the antiderivative. One way to think about it is we're doing the opposite of the derivative operator. In the derivative operator, you get an expression, and you find its derivative. Now what we want to do is, given some expression, we want to find what it could be the derivative of. If someone were to ask you, what is 2x the derivative of? They're essentially asking you for the antiderivative.