This document discusses polygons, including definitions of polygons and different types of polygons such as regular polygons. It provides the names of polygons based on the number of sides from 3 to 11 sides or more. It also gives examples of convex and concave polygons as well as the definition of a regular polygon. The document demonstrates how to find the sum of interior angles of polygons and the measure of each interior angle for a regular polygon. It includes practice problems for finding the angle of regular heptagons and 21-gons. It asks how to find the number of sides of a polygon if the sum of interior angles is given and provides homework problems.