Elasticity of demand is a measure of how responsive the quantity demanded of a good or service is to a change in its price. It is calculated as the percentage change in quantity demanded divided by the percentage change in price.
If the elasticity of demand is greater than 1, the good or service is considered elastic, meaning that a small change in price will lead to a large change in the quantity demanded.
If the elasticity of demand is less than 1, the good or service is considered inelastic, meaning that a small change in price will lead to a small change in the quantity demanded.
If the elasticity of demand is equal to 1, the good or service is considered unit elastic, meaning that a change in price will lead to an equal percentage change in the quantity demanded.
If the elasticity of demand is zero or negative, the good or service is considered perfectly inelastic, meaning that the quantity demanded does not change with a change in price.
It's worth noting that the elasticity of demand also can be affected by other factors, like the availability of substitutes, the proportion of income that the good or service represents, and the time frame in which the change in price is considered