To play a 78 record, one needs a turntable with a variable speed lever, or a vintage turntable designed to play only at 78 revolutions per minute. The 78 was an audio recording format that was popular from the late 19th century up through the 1950s.
A 78 is a kind of physical audio recording. It is usually made of vinyl, though shellac has also been used. "78" refers to the number of revolutions per minute the record needs to spin to transmit audio at the intended quality.
Because 78s were eventually supplanted by 45s, some turntables are not designed to play at 78 revolutions per minute. However, many turntables made in the 1950s had variable speed levers to play a variety of record formats, including the 78 standard.
As of 2015, such turntables are still available for playing 78s. Some of these variable speed turntables can be adjusted to a fine degree. That is important, as many 78s were not recorded at exactly 78 revolutions per minute. Playing a record at the wrong speed can make the audio sound harsh.