This document provides an overview of density functional theory (DFT). It discusses the history and background of DFT. DFT was developed to solve many-body quantum mechanical problems and obtain approximate solutions to the Schrodinger equation for multi-particle systems. The document outlines the Hohenberg-Kohn theorems which established the foundations of DFT and that the ground state electron density uniquely determines the external potential of the system. It also discusses the Kohn-Sham equations which allow DFT to be applied by solving single-particle equations.