12 Principles of Animation
1.SQUASH AND STRETCH
This action gives the illusion of weight and volume to a character as it moves. Also squash and stretch is useful in animating dialogue and doing facial expressions. How extreme the use of squash and stretch is, depends on what is required in animating the scene. Usually it’s broader in a short style of picture and subtler in a feature.
It is used in all forms of character animation from a bouncing ball to the body weight of a person walking.
This is the most important element you will be required to master and will be used often.
Here is an example of squash and stretch on a non cartoon character.