Stop motion (or frame-by-frame) animation is a general term for an animation technique which makes static objects appear to move. The object is moved by very small amounts between individually photographed frames, producing the effect of motion when the series of frames is played as a continuous sequence. Clay figures are often used in stop motion animations, known as claymation, for their ease of repositioning.

Stop motion comes in many forms, often erroneously used interchangeably, causing much confusion of terms in animation literature syntax. Confusing the issue further is the fact that many stop-motion films use more than one technique, such as in Disney's Noah's Ark (1959), the work of Mike Jittlov, and the TV series Robot Chicken.

It is central to the techniques used on popular children's shows such as Gumby and most of the films of Claymation producer Will Vinton and his associates. Clay animation can take the style of "freeform" clay animation where the shape of the clay changes radically as the animation progresses, such as in the work of Eliot Noyes Jr and Church of the Subgenius co-founder Rev. Ivan Stang's animated films, or it can be "character" clay animation where the clay maintains a recognizable character throughout a shot, as in Art Clokey's and Will Vinton's films.

One variation of clay animation is strata-cut animation in which a long bread-like loaf of clay, internally packed tight and loaded with varying imagery, is sliced into thin sheets, with the camera taking a frame of the end of the loaf for each cut, eventually revealing the movement of the internal images within. Pioneered in both clay and blocks of wax by German animator Oskar Fischinger during the 1920s and 30s, the technique was revived and highly refined in the mid-90s by David Daniels, an associate of Will Vinton, in his mind-numbing 16-minute short film Buzz Box.

A final clay animation technique, and blurring the distinction between stop motion and traditional flat animation, is called clay painting (which is also a variation of the direct manipulation animation process mentioned below) where clay is placed on a flat surface and moved like "wet" oil paints as on a traditional artistic canvas to produce any style of images, but with a clay 'look' to them. Pioneering this technique was one-time Vinton animator Joan Gratz, first in her Oscar-nominated film The Creation (1980) and then in her Oscar-winning Mona Lisa Descending a Staircase filmed in 1992.