Collisions: Elastic and inelastic forces
A collision is any event in which two or more bodies exert forces on each other in a relatively short time.
A collision does not necessary involve big forces. For example, when an insect lands on a plant's leaf, its legs collided with the leaf as well as when a boxer throws a punch, their fist is said to collide with the opponent's body.
The following is a list of relevant theory pages: