George Eastman, left, with a fellow inventor, Thomas Edison, in the late 1920s.
George Eastman bought a camera in 1877 and paid someone to teach him how to use it. Then he found an easier way. First he replaced the wet-plate process, in which photographers had to cart chemicals around, with a dry-plate system, so they could just take along Eastman’s precoated glass. Then he replaced the glass plates with paper film, leading to the simpler camera called the Kodak.