Slow motion is an effect resulting from running film through a movie camera at faster-than-normal speed. After recording, when the film is projected at the standard speed, action on the screen seems slowed down.
The effect is often used in coverage of sports events, such as diving, to demonstrate skill and style, or to recapture a key moment in a ball game. These scenes are often shown as a replay.
It can also be used for artistic effect, to create a romantic aura or suspense or naturally to stress a moment in time. Vsevolod Pudovkin, for instance, used slow motion in a suicide scene in The Deserter, in which a man jumping into a river seems sucked down by the slowly splashing waves.
The opposite of slow motion is fast motion.
A VCR may have the option of slow motion playback, sometimes at various speeds; this can be applied to any normally recorded scene.
It is doubtful that the concept of slow motion existed before the invention of the motion picture.