A riff is a short, repeating pattern, melody, or chord progression that forms the basis or accompaniment of a musical composition. It is often played by the rhythm section instruments or solo instrument and can be as simple as a catchy rhythmic figure or as complex as the riff-based variations in the head arrangements played by the Count Basie Orchestra. Riffs are most often found in rock music, heavy metal music, Latin, funk, and jazz, but classical music is also sometimes based on a riff, such as Ravels Boléro. A songs riff is also referred to as its hook, though there is a difference between the two. A hook is designed to simply catch a listeners ear, while a riff gives structure to the song. Riffs are repeated and tend to be the defining melodic element of a song.