Produced from the early 1900s to the 1950s, 78s were the first widely available format for recorded music. Made from shellac and typically 10 or 12 inches in diameter, they were the best available technology until replaced by vinyl 'long playing' records in the 1950s.

78s, especially for blues and regional genres, can mark the only time that artist was recorded.  

They require a turntable with a 78 RPM speed setting and a larger stylus. Some modern cartridges can be 'flipped' to a 78 stylus, but you'll need the correct speed.