Principles Pt 1

The principles of animation are a set of 'rules' that are accepted as the fundamentals to creating a smooth and believable character. These rules were written by two Disney employees - Frank Thomas and Ollie Johnson.
 
The first of the principles is Squash and Stretch. This is where an object changes shape to accommodate for the energy being transferred to it but crucially not in volume. An example of squash and stretch (extreme) can be seen below...

As the ball hit the floor it squashes from the impact, as it begins to jump back up part of the ball delays behind as the other begins to move upwards, this is the stretch. The delay can be called 'follow-through'.

Follow-through is another principle, in this, there is a delay in the movement of one element in relation to another. With the ball, it is a little difficult to see. Another example that is easier to understand is a cape. When someone runs, the cape doesn't immediately gain the momentum of the person pulling it. Instead it takes a small moment for the momentum to reach through the person to the cape before it starts to move in relation. This is called follow-through.

The last principle that the ball example can explain is the 'Arc' movement. This is where most unrestrained objects will move in an arc pattern. When a ball bounces, it does not move back up in a line, instead it uses its angle and bounces off to follow an arc shape.