An early form of animation is the flipbook.
A flipbook is a simple form of animation consisting of a sequence of drawings, or photographs, that when "flipped" through by the viewer appear to create the illusion of motion.
This illusion is an optical phenomenon known as the persistence of vision. It is the result of the eye’s retina retaining an image for about 1/12 of a second. When successive images are shown at a faster rate, the eye will blend them together with the retina retaining one image as the second is superimposed over it. This creates the illusion of movement and is the fundamental principle involved in film and television recording and reproduction. Sound movies have been traditionally projected at 24 frames per second or faster making the illusion of movement very smooth.
This illusion of movement is the fundamental principle in animation.
The customary way to do the flipping technique is to hold the book with one hand while flipping through the pages with the thumb of the other hand.
Today, flipbooks still play an important role in the teaching animation. Using the flipbook technique, an idea for animation can be tested. However, this technique will only work if it is done with enough speed. As an animator, you must master this technique and be able to flip at least five pages on an average.