A sudden turn of the camera from one
subject to another.
Usually when wanting to change the viewpoint one uses a cut, but since we are so used to this a whip pan can be utilized where an element of surprise or confusion as well as a feeling for the distance (short or long) is desired.
Whip pans are not easy to do, as there is often a risk of overshooting the turn, and probably a change of focus to be pulled off simultaneously. The turn begins and ends relatively gradually to let the viewers eyes keep up. All in all a move needing rehearsals to pull off smoothly.