A beet is also a dark purple root vegetable that is great in salads. But seriously folks....A beat is a moment of time. It is often used to clarify phrasing in a shot, to give the viewer more time to understand the moment. It can usually last around 8 to 16 frames and is often a still moment. A beat can be a held pose or a moving hold at the end of a line to make the point. Or a pause in between lines to show thought process, internal dialogue, realization, or confusion. A beat is something that the audience can read because it is not lost with tons of fast movement. A beat is just a clear phrasing moment in the animation that tells you what the object/character is doing. Often, the word beat is used in animation like so: "You need a beat in there." Which essentially just means you need to hold a pose longer or have more time on a certain moment. Usually less then a second.
As for finding where you need beats in shots, look for moments that need to be quieter or read longer. These moments calm down what is going on, as much as possible around the eyes, since that is what the viewer usually wants to focus on. And if need be add a few frames to these moments to have more time to register the pose. Family guy is great for beats. They really draw them out. The movie Kung Fu Panda had many great beats, that allowed time to show the characters thought process. One pet peeve of mine is how so many animated movies are just quick cuts, line, cut, line, cut, and so forth. No moments of silence or thought process to be seen!
In general if you (or your mentor/supervisor) feel your shot is too fast and there is too much going on, adding a beat can help. If the shot is not too time constricted. Usually personal and student work you can play around with time as much as you want. If you are working at a studio and the shot has time constraints, and the director doesn't want to add more time, you have to simplify the animation to be less busy.
Guest blogger jmart (Jason Martinsen)