When was the 45 rpm record invented?

The 45 RPM record was developed by RCA Victor in 1949 as a competing format for the 33 1/3 RPM (33) format of rival Columbia records that premiered in 1948.

Eventually the 45 RPM format (7 inches in diameter with a one-inch center hole) was adopted for shorter recordings while 33 RPM (12 inches in diameter with a 1/4 inch center hole) was used for so called LP (long playing) albums. This eliminated the need to reduce the groove width or quality of 45 RPM recordings.