Lasseter's paper discusses the 11 fundamental principles of animation
developed by Disney that are necessary for achieve entertaining,
personable characters for extended plot sequences.  In the 1920's,
character animations were very simplistic, relying heavily on sight
gags that couldn't possibly sustain a plot lasting longer than several
minutes.  The principles of animation discussed in this paper took
animation from being a "novelty" to a true art form by giving
characters more substance and a richer emotional palette that had the
potential to carry a plot or story thread far longer than any short
film.  The principles of animation necessary to make this happen are:
squish and stretch, timing, anticipation, staging, follow through and
overlapping action, straight ahead action and pose-to-pose action,
slow in and out, arcs, exaggeration, secondary action, and appeal.