A collision is when two or more objects colide with each other while either in movment or while sitting still.

There are three main types of collisions in physics
1) Totally elastic
2) Less elastic
3) Totally inelastic

Less elastic
No kinetic energy is lost. Since KE is not lost, no energy can go into heat or sound
Less damage or heat created
The colliding objects stick together and become one.
Usually involves only collisions where the objects can't touch
Less sound created
Involves the greatest loss of Kinetic Energy.
No damage caused to either colliding object

The colliding objects usually suffer some kind of permanent damage