These principles of animation were written in the year 1981 and are intended originally for the traditional animation but it has become the basis even after development has been introduced. That is why even if it was produced a long time ago, animators use them and they even call it the bible for the animation. The title of the book where they laid down the twelve pricip[les is “The Illusion of Life: Disney Animation”.
The one who wrote it is animators of Disney which is Ollie Johnston and Frank Thomas. They had looked into the work of animators in Disney which are taking the lead in making the animation works. As a result, the work they had done look more to be a real animation. The principles have focused on the physics that is applicable to making animation. They are basic ones and they should be learned. They also include the aspect of the issues regarding abstract. They deal with the appeal of the character and the emotional timing.
The first principle is squash and stretch then anticipation, staging, straight ahead action and pose to pose, follow through and overlapping action. The sixth is slow in and slow out, arc, secondary action, timing, exaggeration, solid drawing, and appeal. These are the twelve principles that even if they were for the traditional but it also became the basic foundation of the use of computer animation. That is why it was even part of the poll on which of two.