Question: what are 45 rpm records?
Answer: The most common form of the vinyl single is the "45" or "7-inch". The names are derived from its play speed, 45 rpm, and the standard diameter, 7 inches. The 7-inch 45 rpm record was released 31 March 1949 by RCA Victor as a smaller, more durable and higher-fidelity replacement for the 78 rpm shellac discs.