What is the cause of elasticity?

Explanation

When the deforming force is applied to a solid, the atoms or molecules are displaced from their equilibrium positions and the interatomic or intermolecular distances get changed. As a result of this change in intermolecular separation, restoring force is set up in the solid. When deforming force is removed, this restoring force brings the atoms or molecules back to their original position and the body acquires the original configuration.