Terrence Mitchell "Terry" Riley is an American composer and performing musician best known as a pioneer of the minimalist school of composition. Influenced by jazz and Indian classical music, his work became notable for its innovative use of repetition, tape music techniques, improvisation, and delay systems. His best known works are the 1964 composition In C and the 1969 album A Rainbow in Curved Air, both considered landmarks of minimalism and important influences on experimental music, rock, and contemporary electronic music. Subsequent works such as Shri Camel (1980) explored just intonation.

In C is a musical piece composed by Terry Riley in 1964 for an indefinite number of performers. He suggests "a group of about 35 is desired if possible but smaller or larger groups will work". A series of short melodic fragments that can be repeated at the discretion of musicians, In C is often cited as the first minimalist composition to make a significant impact on the public consciousness.