Now, for fun, let's define a function capital F of x. And I will do it in blue. Let's define capital F of x as equal to the definite integral from a, from a as a lower bound, to x of f of t, of f of t, dt, where x is in this interval. Where a is less than or equal to x is less than or equal to b. Or that's just another way of saying that x is in this interval right over here. Now, when you see this, you might say, oh, you know, the definite integral, this has to do with differentiation and antiderivatives and all that. But we don't know that yet.