Long-playing (LP) record albums are 33⅓ rpm, typically vinyl, gramophone records (phonograph records), generally either 10 or 12 inches in diameter. They were introduced unsuccessfully by RCA in 1931 and successfully by Columbia in 1948, and served as a primary release format for recorded music until the compact disc began to significantly displace them in the 1980s. In the 21st century, a renewed interest in vinyl has occurred and the demand for the medium has been on a steady increase yearly in niche markets. The long-playing record is an analog format.
For more on the history of the LP, see Wikipedia