This chapter introduces the readers to different types of elasticities, their importance, and applications to the real world. After reading this chapter and working on the practice questions, the learners should be able to interpret the meaning of elasticity coefficients (such as price elasticity of demand, price elasticity of supply, cross-price elasticity, and income elasticity of demand); calculate elasticity coefficients; differentiate between elastic and inelastic demand/supply; and evaluate the importance and understand the applications of elasticity coefficients to the real world.