In physics , elasticity (from Greek ἐλαστός "ductible") is the ability of a body to resist a distorting influence or deforming force and to return to its original size and shape when that influence or force is removed. Solid objects will deform when adequate forces are applied on them. If the material is elastic, the object will return to its initial shape and size when these forces are removed.
Elasticity is one of the most important concepts in neoclassical economic theory. It is useful in understanding the incidence of indirect taxation , marginal concepts as they relate to the theory of the firm , and distribution of wealth and different types of goods as they relate to the theory of consumer choice . Elasticity is also crucially important in any discussion of welfare distribution, in particular consumer surplus , producer surplus , or government surplus .