A two-channel audio system with the channels designated as left and right.
Devised primarily because we have two ears, stereo reproduction of recorded sound has been the norm for many decades as it offers an excellent representation of what we hear acoustically. Any multitrack recording has to be mixed to stereo in order for it to be played on a standard domestic hi-fi system. When played back simultaneously the audio system will create a 'phantom' imaginary centre image. See also - Panning