Demand can be classified as elastic, inelastic or unitary. An elastic demand is one in which the change in quantity demanded due to a change in price is large. An inelastic demand is one in which the change in quantity demanded due to a change in price is small.
The elasticity of demand is the change in demand due to the change in one or more of the variable factors that it depends on.The responsiveness of the quantity demanded to the change in income is called Income elasticity of demand while that to the price is called Price elasticity of demand.
Elastic demand or supply curves indicate that the quantity demanded or supplied responds to price changes in a greater than proportional manner. An inelastic demand or supply curve is one where a given percentage change in price will cause a smaller percentage change in quantity demanded or supplied.