Elasticity measures the extent to which demand changes in response to a change in price. There are different degrees of price elasticity including perfectly elastic, perfectly inelastic, unitary elastic, relatively elastic, and relatively inelastic demand. Cross elasticity and income elasticity also measure responsiveness of demand but to other factors like substitute goods and consumer income levels respectively. Methods for measuring price elasticity include the total expenditure method, percentage method, point method, arc elasticity, and revenue method.
