This document discusses elasticity and its application. It defines elasticity as a measure of how much buyers and sellers respond to changes in market conditions. It then discusses types of elasticity including price elasticity of demand, income elasticity of demand, and cross price elasticity of demand. Price elasticity of demand measures the responsiveness of quantity demanded to a change in price. The document provides formulas and examples for computing different elasticities. It also outlines factors that determine the elasticity of demand.