12 Principles of Animation: Follow Through and Overlapping Action

The Follow Through and Overlapping Action are the techniques from the 12 Principles of Animation that are utilized for the details of the character corresponding to his movement. Follow Through is the termination of an occurring action and all additional movements which gradually stabilize after the movement has stopped. In other words, when a character is running, the moment he stops the rest of his body (movements of his hand, clothes, etc...) lag in motion for a brief period, to make the character more vivacious. Overlapping, on the other hand, is where a second action follows the first and the character's details (hair, clothes, etc...) move in compliance to the motion of the character.

Emperor's New Groove: https://www.youtube.com/watch?v=km40jvV5lhM

For example, during the 0:13 mark of the video, the character runs down the stairs, exhibiting Overlapping, while when he stops the bag and his hair continue their motion for a short while until they stabilize, which is the Follow Through action.