Chorus is a modulation effect that thickens and widens a sound by duplicating the signal, slightly detuning it, and modulating its pitch over time. This creates the impression of multiple instruments playing together, resulting in a rich, shimmering, and spacious tone.

It is commonly used on guitar, bass, and keyboards to add movement and depth, working especially well with clean or lightly driven sounds. Chorus became strongly associated with 1980s music but remains widely used across pop, rock, ambient, and modern styles for its ability to make a sound feel fuller and more animated.