This document provides an overview of surface characterization techniques using low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED). It discusses the instrumentation, principles, and applications of LEED and RHEED. LEED uses elastic scattering of electrons to determine the structure of crystalline surfaces. RHEED similarly uses electron diffraction but is more surface sensitive due to the grazing angle of incidence. Both techniques provide information on surface structure, phase transitions, crystal growth, and more through analysis of diffraction patterns and intensity variations.