Zoetropes: Several designs and children's toys experimented with the idea of rapidly presenting a series of static images to create the illusion of motion. But not until 18-year-old William Lincoln presented his design to Milton Bradley did the design take off. The trick was to place slits in the viewing device so that the images would only be seen briefly and not continuously. This persistence of vision, the fact that an image remains visible after it is removed, is what allows movies, a series of still images, to be seen in motion:
