Elasticity is the measure of behaviours by producers and consumers in response to changes in price. It is the conic term which measures how the supply and demand is affected and changed because of an increase or decrease in price. A factor that gains importance once prices are changed is the availability of substitutes. If substitutes are available at a more convenient price then people may switch to them. This would decrease the demand for the product whose price was canted and it will also affect the supply (and demand) for the substitute product.