the lp (from "long playing" or "long play") is an analog sound storage medium, a phonograph record format characterized by a speed of  rpm, a 12- or 10-inch (30- or 25-cm) diameter, and use of the "microgroove" groove specification. introduced by columbia in 1948, it was soon adopted as a new standard by the entire record industry. apart from a few relatively minor refinements and the important later addition of stereophonic sound, it has remained the standard format for record albums.