This document provides an overview of different systems for classifying malocclusion. It describes Angle's classification system, which is based on the relationship between the maxillary first molar and mandibular first molar. It also discusses modifications to Angle's system by Dewey, Lischer, Bennet, Simon, and Ackermann-Profitt. The classifications help with diagnosis, treatment planning, communication, and comparisons by describing deviations from normal occlusion.