This document provides an overview of molecular beam epitaxy (MBE) for thin film deposition. MBE involves heating pure elements in separate cells and evaporating them as molecular beams in ultra-high vacuum onto a substrate. This allows for layer-by-layer crystal growth at slow deposition rates. Key aspects of MBE include the use of shutters and in-situ diagnostics to control layer thickness and monitor crystal quality. Challenges include stresses that can cause cracking in films with large lattice mismatches to the substrate.