Reverse motion (also known as reverse motion photography or reverse action) is a special effect in cinematography whereby the action that is filmed is shown backwards (i.e. time-reversed) on screen. It can either be an in-camera effect or an effect produced with the use of an optical printer. There are various reasons why this technique may be adopted, such as for comedic effect (destruction reversal) or for safety reasons (a car stopping just in time may be filmed starting at the stop point).