Math rock is a rhythmically complex, often guitar-based, style of rock music that emerged in the late 1980s in the American indie rock scene, influenced by post-hardcore, progressive rock bands like King Crimson and 20th century minimalist composers such as Steve Reich. It is characterized by complex, atypical rhythmic structures (including irregular stopping and starting), counterpoint, odd time signatures, angular melodies, and extended, often dissonant, chords.