Bringing drawn objects to life is the literal meaning of the animator's job. While the methods for doing so have evolved over the years (and are now almost entirely digital), the underlying principles of making drawn life convincing haven't really changed. A dozen of them were set out in the 1980s by the seminal The Illusion of Life — a book by two of the master Disney animators, Frank Thomas and Ollie Johnston — and have now been recreated for the web in GIF form. You'll find a video detailing the importance of exaggeration, timing, and charisma below, with the full set of 12 GIFs at the source link.