Chinese music has a long history and incorporates many different styles. Traditional Chinese music is based on Chinese philosophy and utilizes a pentatonic scale. Poetry and narrative songs are commonly sung, while opera features acrobatics, dancing, and elaborate costumes. Folk music includes lively dance music and occasional erotic songs. Chinese music employs a wide variety of instruments categorized by the material used, and each instrument is associated with a season or direction. Popular modern Chinese music includes Cantopop, a fusion of Western pop with Chinese styles.