Thomas Edison's sprocket holes set the world movie standard

In the late 19th century, watching a movie was a gamble; one theater might use 22mm film while another used 70mm, making it impossible to share reels between cities. Thomas Edison realized that controlling the physical format meant controlling the industry. In 1891, he settled on 35mm wide strips of celluloid, but the real genius lay in the four small holes punched along the sides of every frame. These 'perforations' allowed gears to pull the film through a projector with surgical precision.