Elasticity is the measure of the responsiveness of one variable to changes in another. Economists have identified four main types.
[PRICE ELASTICITY] measures how much the quantity of [SUPPLY] of a good, or DEMANDfor it, changes if its [PRICE] changes. If the percentage change in quantity is more than the percentage change in price, the good is price elastic; if it is less, the good is [INELASTIC].
Income elasticity of demand measures how the quantity demanded changes when income increases.