The word calculus comes from a latin word meaning small stones and is like understanding something by looking at small pieces. It can be used to find areas, volumes, central points and many useful things. Integrals can be of the type : single integral, double integral, multiple integrals. Generally these are used to find surface area and the volume of geometric solids. Integrals together with derivatives are the fundamental objects of calculus. Integral calculus is also known as antiderivative and primitive. Integrals are commonly of two types : Definite integrals and the indefinite integrals .