The document discusses the concept of demand and factors that influence it. It defines the law of demand, which states that as price increases, demand decreases, and as price decreases, demand increases. It then explains demand curves and how they illustrate the relationship between price and quantity demanded in the market. It also defines elasticity of demand and the factors that determine whether demand is elastic or inelastic, such as availability of substitutes and whether the good is a necessity or luxury. Finally, it discusses how non-price factors can cause the demand curve to shift, such as changes in income, prices of substitute or complementary goods, attitudes, and scarcity.