The property by virtue of which a material body regains its shape, size and original configuration on removing deforming force is called elasticity.
The property by virtue of which a material body cannot regain its original shape, size and configuration is called plasticity.
Perfectly elastic body
A body which regains its original configuration completely and instantaneously after the removal of the deforming force is called perfectly plastic body. However, nobody is perfectly elastic. So, perfect elasticity is an ideal concept. The body which approaches the closest to perfectly elastic is quartz fiber.
Perfectly plastic body
A body which doesn’t regains its original configuration on removing how so small deforming force is called perfectly plastic body. The concept of perfectly plastic is an ideal concept because nobody is perfectly plastic. The body which approaches closest to perfectly plastic is paraffin wax.