A zoetrope is a pre-film animation device that produces the illusion of motion, by displaying a sequence of drawings or photographs showing progressive phases of that motion. A zoetrope is a cylindrical variant of the phenakistiscope, an apparatus suggested after the stroboscopic discs were introduced in 1833. The definitive version of the zoetrope, with replaceable film picture film strips, was introduced as a toy by Milton Bradley in 1866 and became very successful.