A phonograph record is a storage disk with grooves that convert sound vibrations into electric signals and music. The first records evolved from phonautographs in the 1850s, which recorded sound but could not be played back. Thomas Edison's 1877 phonograph and Graham Bell's hand-cranked gramophone made flat discs easier to play, resulting in the vinyl record.
Early 20th-century records were made from shellac and had varying speed and design. By the 1920s, they were standardized to 78 rpm, with the ten-inch record holding three minutes per side. Playing times varied slightly depending on the speed-to-diameter ratio, with 12-inch records holding five minutes and rare 21-inch records having eight.
The LP marked a significant milestone in record evolution, with its narrower grooves and slower speeds. RCA Victor launched the first LP in 1930, but the Great Depression hindered sales. Columbia's 1948 vinyl LP perfected the technology, allowing bands to jam as much music as possible on each side. Album covers showcased band members or artistic visions.