Squash and stretch is a key animation principle that allows dramatization and deformation of an object to create the feeling of flexibility, mass and life in animation. This specific aspect of animation can let an object grow wider, or shrink thinner (squishing). The same can be said about stretching. Animators use this technique to convey an effect of impact, movement, and even bouncing. 

Here are the key values of squash and stretch:

• Weight: This allows the audience to understand the density of the object. Keeping weight in mind allows more immersion in the animation, along with a deeper understanding of the situation.

• Flexibility: Weight and flexibility are always used together. If a ball is light, it is more likely to extend or squish when exposed to pressure.

• Volume: If a shape alters, the volume will never change. It is vital to keep this in mind.