A video tape recorder (VTR) is a tape recorder designed to record video material on magnetic tape. The first practical video tape recorder, using transverse tape head scanning, was developed by Ampex Corporation in 1956. The early VTRs were reel to reel devices which recorded on individual reels of 2 inch (5.08 cm) wide magnetic tape. They were used in television studios, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. Beginning in 1963, videotape machines made instant replay during televised sporting events possible. Improved formats, in which the tape was contained inside a videocassette, were introduced around 1969; the machines which play them are called videocassette recorders. Agreement by Japanese manufacturers on a common standard recording format, so cassettes recorded on one manufacturer's machine would play on another's, made a consumer market possible, and the first consumer videocassette recorder was introduced by Sony in 1971.