Inertial Frame: An inertial frame is a special type of reference frame where Newton's laws of motion hold true without any external forces acting on it.
Non-inertial Frame: A non-inertial frame is a reference frame that is accelerating or rotating. In this type of frame, additional fictitious forces need to be considered.
Relative Motion: Relative motion refers to the movement of an object with respect to another object or observer. It describes how one object's motion appears from the perspective of another object or observer.