Stop Motion is an animation technique.
It requires a motion picture camera that can expose single frames. It works by shooting a single frame, stopping camera to move the object a little bit, and then taking another photograph. When the film runs continuously, it appears that the objects move by themselves. This is similar to the animation of cartoons. The great American pioneer of this technique was Willis O'Brien, who animated King Kong. His studentRay Harryhausen made a number of movies with the same technique. More recently, it's used in the works of Aardman Animations Wallace and Gromit films.