celluloid

Celluloid is really several pictures strung together especially in the case of animated movies. Character development, sketching, visualization and continuity are key elements for an animator to imbibe.
Storyboards are graphic organizers in the form of illustrations or images displayed in sequence for the purpose of pre-visualizing a motion picture, animation, motion graphic or interactive media sequence.

The storyboarding process, in the form it is known today, was developed at Walt Disney Productions during the early 1930s, after several years of similar processes being in use at Walt Disney and other animation.

information and photo credits:

http://animationtidbits.tumblr.com/post/74387430941/frozen-paul-briggs

http://en.wikipedia.org/wiki/Storyboard