Combinatorics is a branch of mathematics that studies the size and structure of discrete sets. This allows us to enumerate and evaluate the sample space of performing various actions on these sets. As a result, a mastery of combinatorics is vital in order to understand probability. Combinatorial problems also applies in various other areas of science, including economics, statistical physics, and graph theory. In this module, we will cover the basics of combinatorics, highlighting the importance of the binomial notation, and introduce an application of one-to-one correspondences.