“Elasticity of demand may be defined as the percentage change in quantity demanded to the percentage change in-price.”However, some particular values of elasticity of demand have been explained as under:1. Perfectly Elastic Demand:Perfectly elastic demand is said to happen when a little change in price leads to an infinite change in quantity demanded. A small rise in price on the part of the seller reduces the demand to zero. In such a case the shape of the demand curve will be horizontal straight line .(ed=∞)✓2. Perfectly Inelastic Demand:Perfectly inelastic demand is opposite to perfectly elastic demand. Under the perfectly inelastic demand, irrespective of any rise or fall in price of a commodity, the quantity demanded remains the same. The elasticity of demand in this case will be equal to zero (ed = 0).✓3. Unitary Elastic Demand::The demand is said to be unitary elastic when a given proportionate change in the price level brings about an equal proportionate change in quantity demanded. The numerical value of unitary elastic demand is exactly one i.e. Marshall calls it unit elastic.(ed=1)This demand curve is called rectangular hyperbola.✓4. Relatively Elastic Demand:Relatively elastic demand refers to a situation in which a small change in price leads to a big change in quantity demanded. In such a case elasticity of demand is said to be more than one (ed > 1). ✓5. Relatively Inelastic Demand:Under the relatively inelastic demand, a given percentage change in price produces a relatively less percentage change in quantity demanded. In such a case elasticity of demand is said to be less than one (ed < 1).✓="" />