With number theory quals in mind, I will give a brief introduction to Dirichlet characters and some applications. The first lecture will introduce these characters and discuss principal, induced, and primitive characters. In addition, we will look at Gauss sums, which connect multiplicative characters to additive characters. In a future lecture or lectures, I will prove the Polya--Vinogradov inequality (for a sum of character values over an interval) plus an application to primitive roots. A resource for the material up through Polya--Vinogradov is Davenport's ``Multiplicative number theory".