Stop motion is a filming technique used to create animation sequences using any type of object whose characteristics and position can be manipulated (including living beings).
The object or objects are manipulated in increments which are individually photographed. Manipulation of the objects is usually carefully orchestrated in order to produce a desired effect. The individual images are then put together into a playable film. Playing the film creates the illusion that the manipulated objects are moving.
A famous example of a film incorporating stop motion animation is King Kong (1933).
Stop motion animation using pliable materials such as plasticine or clay is referred to specifically as clay animation or claymation. The most well-known examples of this technique are probably the Wallace & Gromit films by Nick Park of Aardman Animations.
See our review of Tim Burton’s stop motion animation, Frankenweenie (2012).