Within the history of animation, there has been many methods of creating a mass amount of drawn or digital art that have merged together to become a sequence to create a moving picture. The earliest technique that was well known is the zoetrope. The zoetrope creates an illusion to the human eye of a moving image from one static image to another by rotating at a certain speed as the human eye cannot pick up each frame. The zoetrope is a cylindrical spinning device with several frames of animation printed on a paper strip placed around the interior circumference.
Here is an example I manage to find that could explain the most simplistic way of describing how the animation works. From this video you see how the image transcends from the previous frame to the next while the eye fills in the missing blank between each frame to show the smooth movement of the drawing.
After the zoetrope was invited there was a more precise and better adaptation which was called the praxinoscope which was invented in France in 1877 by Charles-Émile Reynaud. And the difference between the zoetrope and this new praxinoscope is that there both still early and original forms of animation going from one moving image into a sequence looking as if it was a video by looking at a certain angle. The Praxinoscope also has improved by replacing its narrow viewing slits with an inner circle of mirrors placed so that the reflection of the pictures appeared more or less stationary in position as the wheel turns.
An example of this is here:
Physics.kenyon.edu. n.d. Praxinoscopes. [online] Available at: http://physics.kenyon.edu/EarlyApparatus/Optical_Recreations/Praxinoscopes/Praxinoscopes.html [Accessed: 21 Feb 2014].