If you are an animator, you need this book. If you're interested in animation, you want this book. In my opinion, as books about the theory and practice of animation goes, there are only about two or three in the must-have class. This one did Leads pack. In Particular, the "Principles of Animation" chapter is the clearest and best explanation of the principles of animation in existence. If you're on animator, you need to know these rules, whether or not you intend to break them.