78 RPM records are a type of phonograph record that were popular from the late 19th century until the mid-20th century. The term "78 RPM" refers to the speed at which the record spins, which is 78 revolutions per minute. These records are typically made of shellac, a natural resin, and are thicker and more brittle than modern vinyl records. The sound quality of 78 RPM records is often characterized by a distinct, warm tone, but they have limitations in terms of playback time, usually lasting only a few minutes per side. As technology advanced, 33 RPM and 45 RPM records became more popular, leading to the decline of 78s in the music industry.