The constant of integration in the solution of a differential equation is a member of the latter’s continuous symmetry group, a group of transformations that map one solution to another solution of the equation and also leave the equation invariant-- this crucial observation was made by the Norwegian mathematician Marius Sophus Lie in the second half of the nineteenth century. Lie aimed to construct a general theory of integration that would consolidate the existing disparate methods of integration. He successfully showed that knowledge of a symmetry group of a differential equation leads to quadrature or reduction in order. In particular, he introduced the use of the infinitesimal properties of a continuous symmetry group in his work. This seminar, comprising some rudimentary theory and a simple application in the form of an algorithm used to solve a first order ordinary differential equation, is meant to be an introduction to the very basics of Lie symmetry methods.