The 12 basic principles of animation were developed by the ‘old men’ of Walt Disney Studios, amongst them Frank Thomas and Ollie Johnston, during the 1930s.
The Illusion of Life : Disney Animation
Of course they weren’t old men at the time, but young men who were at the forefront of exciting discoveries that were contributing to the development of a new art form. These principles came as a result of reflection about their practice and through Disney’s desire to use animation to express character and personality.
Frank Thomas & Ollie Johnstone
This excellent short movie is about those principles, applied to simple shapes.
Like a cube
Check also the animated gif gallery