Cross Elasticity of Demand: Cross elasticity of demand measures how responsive the quantity demanded of one good is to a change in the price of another good.
Income Elasticity of Demand: Income elasticity of demand measures how responsive the quantity demanded is to a change in income.
Substitutes and Complements: Substitutes are goods that can be used as alternatives to each other, while complements are goods that are consumed together. The concept of substitutes and complements plays a role in determining price elasticity of demand.