LPs
LPs (Long Playing record) also known as an "album" were invented in 1948. The 33 1/3 LP was released by Columbia Records. The preferred disc for singles became the large-hole 45rpm records by RCA Victor in 1949. The 45rpm record was 7". In 1952 the Recording Industry Association of America was formed. There was the 33-1/3rpm LP, the 78rpm, and the 45rpm at 12", 10" and 7". in 1955 the 12" became more popular than the original 10" LPs.
