The animation principles are fundamental terms that were created by Disney animators to describe successful animation processes. The terms were first found in The Illusion of Life: Disney Animation a book written by two of Disney’s Nine Old Men, Ollie Johnston and Frank Thomas. Johnston and Thomas created these terms by studying the work of lead animators before them. Disney has been using these principles since the 1930's, but the public only integrated these principles as rules of animation after the book's release in 1981. The principles are categorized into the following twelve animation processes:
1. Squash and Stretch is the key principle that gives the illusion of what the weight and mass of the animated object is and how flexible it can become.
2. Anticipation is how animators prepare the audience for what is about to happen next.
3. Staging demonstrates clearly who the character is by using placement in a frame, lighting, environment or character props and camera position.
4. Straight Ahead Action and Pose to Pose describes two processes of animated. The first allows for a free-form style while the second benefits from planned layouts regarding character poses.
5. Follow Through and Overlapping Action helps illustrate that everything in an action happens at separate times.
6. Slow In and Slow Out refers to the speed an action is initiating and ending at.
7. Arcs are paths that occur naturally in organic movement.
8. Secondary Action is an action that enhances the main action that is being performed.
9. Timing refers to the number of frames and the space it takes to perform an action.
10. Exaggeration emphasis the action or personality of a character.
11. Solid Drawing illustrates the action of the character through strong poses.
12. Appeal allows audiences to find the characters interesting.