A definite integral is a more focused form of a mathematical tool called an indefinite integral. When using indefinite integrals, any integrated function or curve must have the arbitrary constant C added to it because the function could be anywhere along the y-axis. In a definite integral, limits of integration are defined so that the function has a set range of boundaries within which it can be integrated. Definite integrals are an extremely important part of Calculus, and are usually considered the most annoying part as well because of the tedious calculations required to solve them. They are mostly used in physics and science where any continuously changing function needs to be evaluated. They are also used in manufacturing when the volume of an irregular shape needs to be found.