Persistence of Vision and the Zoetrope

Persistence of vision means that when we see a series of images together, that are subtly different, our brain relates the previous image to the current one and relates them to one another, so we see them as them as a moving picture - a video.

A form of early animation, which used the theory of persistence of vision, was the Zoetrope. To see the images, you had to look through one of the slits on the side, and when spun, the inside images would move and it would look as if they were moving.

Here is an example from YouTube: