This document discusses calculating the perimeters of polygons. It defines perimeter as the distance around a shape and explains how to find the perimeter by adding up all the length and breadth measurements of the sides. An example is shown of calculating the 34cm perimeter of a 12cm by 5cm rectangle. Formulas are introduced for the perimeter of a rectangle as 2 times the length plus 2 times the breadth, written as 2L + 2B. Other regular shapes where not all sides need to be measured are mentioned.