Timing

This is the principle which takes the most practice to learn no matter whom you are as an animator, as it is possibly the most crucial of them all. Yet it is the easiest to understand it is simply the time it takes to perform an action. Within animation this can be a useful aid in exaggerating action for mood or narrative purposes. A simple thing like a ball bouncing needs to abide the laws of physics enough to project the illusion of believability so that the audience can understand what is going on. Yet, like many other things in animation these laws can be bent and as long as you consider the weight vs. momentum (animators need to understand how an object would react if said object or being were to react to say a push,) and you can achieve what would be impossible to do in real life, this is when this principle slims into the realm of what is called theatrical timing.
The key is to imagine invisible weight within your characters in which you are motioning not only this but also the size and a personality. As everyone has their quirks and special ways of walking, even something as simple as a hair flick may be motioned in a particular way. ‘Timing is critical for establishing a character's mood, emotion, and reaction,’ especially when it is a director’s wish to get the audience to feel empathy towards their characters. It is the most successful of animators that are truly able to imitate and exploit this skill as that is when they begin to develop their own sense of ‘style’ into their characters. Many animators when they’re stuck get others to act in the way they want their individuals to move as a visual aid.