Elastic bodies: The bodies which rebound after impact are called elastic bodies.
The impact between two rubber spheres is an elastic impact.

Inelastic bodies: The bodies which does not rebound at all after its impact are called inelastic bodies.
The impact between two lead spheres or two clay spheres is approximately an inelastic impact.

Coefficient of restitution is defined as the ratio of Relative velocity after impact to Relative velocity before impact. Coefficient of restitution is denoted by 'e'.
e = 0, For perfectly inelastic bodies .
e = 1, For perfectly elastic bodies.
0>e>1,(value of e lies between zero and one) For bodies neither perfectly inelastic nor perfectly elastic.

When two elastic bodies collide with each other
* the two bodies will momentarily come to rest after collision
* the two bodies tend to compress and deform at the surface contact
* the two bodies begin to regain their original shape