In stereophonic sound, sound is recorded on two different channels and then mixed or blended back together, for an observable effect in playback. This is in contrast to monophonic sound, which involves only one channel.
Stereophonic sound is also known as stereo sound or stereo.
Techopedia explains Stereophonic Sound
Common methods for creating stereophonic sound involve the placement of two or more microphones for capturing different sound channels, and sophisticated mixing using state-of-the-art sound equipment. The result is that the listener can hear audio in a kind of distributed field.
One of the enduring issues with stereo sound is how to deliver it through audio hardware. As the "hi-fi" systems of the pre-digital age emerged, they were designed with stereo features. In general, multiple speakers are set up to offer stereo sound experiences. The application of stereo to digital sound is another field, where engineers look to accommodate this more refined sound in new equipment and devices.