Cell refers to each of the thousands of hand-drawn sheets (of clear, transparent material, either celluloid or Mylar). It represents a single animation frame to allow several layers of composition.

Cells consist of character cells (containing only the foreground characters or objects) and background cels (static drawings of scenery that remain the same). Animators place the character cels against the background cels and film one frame (or picture) at a time to produce the effect of motion.

Celluloid also refers to the thin strip of transparent plastic coating that forms the film’s highly flammable, light-sensitive base layer (such as nitrate or acetate base). Celluloid also refers to an adjective related to some aspect of cinema (i.e., “the celluloid hero”). The light-sensitive substance coating on one side of the film base is termed emulsion. Celluloid is also a slang word for a movie.