(Mathematics - Calculus)

For a positive function on the real line, the integral of that function over an interval describes the area between the function's curve and the zero line.

There are several kinds of integration. Most commonly known is the Riemann integral. Other integrals include, but are not limited to, the Darboux integral and the Darboux-Stieltjes integral. Riemann integrals and Darboux integrals are very similar because if a function is Riemann integrable, then it is Darboux integrable and vice versa, and the integrals have the same values. The Darboux-Stieltjes integral is a generalization of the Riemann integral, and appears in the study of probability.