Multitrack recording is a method of sound recording that allows for the recording and re-recording of multiple sound sources, independent of time.
Multitrack recording devices are available with varying capacities (number of simultaneous tracks available for recording). When recording a segment of audio, which is also known as a track, audio engineers and musicians may select which track or tracks on the device will be used.
Each of the tracks available on the recording device may be set to record or to playback. For example, a musician may record onto track 2 and listen on track 1 at the same time. This allows the musician to sing or to play a duet in harmony with a performance already recorded on track 1.
Both performances can then be played back perfectly synchronised, as if they had been played together. This is a type of overdubbing and can be repeated until all of the tracks are used up.
The first musician to use multitrack technology was guitarist Les Paul, and Ampex, an American audio company, released commercial multi-track recorders in 1955, naming the process "Sel-Sync" (Selective Synchronous Recording). The earliest multitrack recorders were analog magnetic tape recorders with 2 or 3 tracks.
The artistic potential of the multitrack recorder came to the attention of the public in the 1960's, when artists such as The Beatles and The Beach Boys began to use multitrack recording extensively, and from then on virtually all popular music was recorded in this manner. The technology developed very rapidly during this time -- at the start of their career in 1963, The Beatles recorded in mono on 2-track machines; by 1965 they were using 4-track to create pop music of unprecendented complexity. In the late Sixties they progressed rapidly through 8-track and 16-track recorders, and their final album Abbey Road in 1969, was recorded on one of the first 24-track machines.
Today multitracks can be analog or digital, and are available with many more tracks. Analog multitracks can have up to 24 tracks and use magnetic tape which is up to 2 inches wide. Digital multitracks can have an almost unlimited number of simultanious tracks and can record to and playback from a number of media and formats including digital tape, hard disk, and optical disk.