Impact:  It is a collision between two bodies which continues for a short interval of time and during which both bodies exert large amount of force on each other. 

Direct Impact: If the velocities of two particles are along the line of impact, the impact is called direct impact. It is also defined as the collision between 2 bodies that are moving along the line of impact.

Oblique Impact: If both particles move along a line other than the line of impact the type of impact is called oblique impact.