Integration is about finding the surface s, given a, b and y = f(x). The formula for the integral from a  to b, graphed above, is:
    Formula:   \displaystyle{ \int\limits_{a}^{b} f(x)\,dx }

What is the integral (animation)

In calculus, an integral is the space under a graph of an equation (sometimes said as "the area under a curve"). An integral is the reverse of a derivative, and integral calculus is the opposite of differential calculus. A derivative is the steepness (or "slope"), as the rate of change, of a curve. The word "integral" can also be used as an adjective meaning "related to integers".