Multitrack recording (MTR)—also known as multitracking, double tracking, or tracking—is a method of sound recording that allows for the separate recording of multiple sound sources or sound sources recorded at different times to create a cohesive whole. Multitracking became possible with in the mid-1950s when the idea of simultaneously recording different audio channels to separate discrete "tracks" on the same tape was developed. A "track" was simply a different channel recorded to its own discrete area on tape whereby their relative sequence of recorded events would be preserved, and playback would be simultaneous or synchronized.