Integration is often introduced as the reverse process to differentiation, and has wide applications, for example in finding areas under curves and volumes of solids. This section explains what is meant by integration and provides many standard integration techniques.

# Integration by substitution

There are occasions when it is possible to perform an apparently difficult piece of integration by first making a substitution. This has the effect of changing the variable and the integrand. With definite integrals the limits of integration can also change. Video tutorial 36 mins.