The Schur functions are a basis for \Gamma, the ring of symmetric functions. They can be expressed as a generating sum for Young tableaux. They are very important, as they appear in geometry (the cohomology of the Grassmannian), representation theory of the symmetric group, among many other applications. The k-Schur functions are a basis for an important subring of \Gamma. They appear in the quantum cohomology of the Grassmannian, as well as the cohomology of the affine Grassmannian. They can be expressed as the generating series of certain objects in which the affine symmetric group has an action on. In this talk we will give a quick review of Schur functions, and then introduce the k-Schur functions and their main properties. This will lay the groundwork for the next two talks on this topic, by Kelli and Dave.