In this series of talks, we cover the current finite difference, finite element, and discontinuous Galerkin methods used to approximate the solutions of second-order elliptic fully nonlinear PDEs. In part one, we introduce examples of some simple fully nonlinear PDEs and outline the solution theory of these equations. Classical solutions of fully nonlinear PDEs rarely exist and thus we cover the viscosity solution concept used to solve them. Existence and uniqueness theory for viscosity solutions is summarized using Perron's method and the vanishing viscosity method. We finish by mentioning two second- order equations which will be our focus for the remainder of the series: the Hamilton- Jacobi-Bellman equation and the Monge-Ampère equation.