This document discusses the economics of demand. It begins by defining demand and the law of demand, which states that quantity demanded varies inversely with price, all else equal. It then explains the concepts of the demand curve and demand schedule. Individual demand curves can be added together to form a market demand curve. The document also covers elasticity of demand, how it is calculated, and factors that influence elasticity like availability of substitutes. It provides examples of elasticity estimates for different products and concludes by discussing other determinants of demand like income, prices of related goods, and consumer tastes and expectations.