Animation is divided into three categories: traditional animation (includes cel-animation), stop motion (includes claymation), and CGI (computer generated imagery). Even today, as it was often done in the past, any one of them may be congruently combined or even used with live-action, e.g. “Who Framed Roger Rabbit?" (1988).
Traditional animation was at one time the most popular type of animation, dating back to the early use of animation in films. Traditional, or classical animation as it’s also called, originally consisted of hand-drawn images on each, single frame, including the background. Later, with the invention of cel-animation, founded by Earl Hurd in 1914 (while employed at John Bray Studio), animation would progress even further.
Cel-animation was a technique used in which the animated ink drawings were inked directly onto clear pieces of celluloid, each frame individually. Then, each piece of celluloid, one at a time, was placed on a single painted background and then photographed consecutively. Since this saved plenty of time, because the background didn’t have to be reproduced for each frame, other animation studios began copying this technique. Today, traditional animation is done digitally on a computer, with “digital ink".
*Even though Earl Hurd, in 1914, invented the cel-animation technique, unfortunately, it was John Bray Studio who received the credit for this innovative method. It was misfortunate that the early animation studios didn’t credit their artists and only thought of fame and monetary gains for themselves.
Otto Messmer, “Felix the Cat" creator, when employed by the Pat Sullivan Studio, experienced the same unfairness as Hurd. Not once in his entire life did he receive recognition or even monetary gain (Pat Sullivan made millions from Messmer’s creation). This also happened at the Walt Disney Studios; except Disney is said to have acknowledged his artists; however, Disney, like Pat Sullivan, received millions from his artists’ creations. For instance, it was Freddie Moore (Robert Fred Moore) who should have received the public attention (while he was alive) for his innovative style towards realistic motion; this exceeded beyond the ‘rubber hose’ style of the day.