There are many genres of music that can be classified according to their purpose. Vocal genres include a cappella music performed without instruments. Instrumental genres involve only instruments and can be pure or descriptive music. Vocal and instrumental genres combine both voices and instruments, like a rock band. Religious genres are composed for religious contexts and can be liturgical or non-liturgical. Profane genres are not for religious purposes and include popular folk, light, and cultured music. Functional genres provide background music for events like the Olympics. Cinematographic genres reinforce films, theatrical genres are for stage performances, and advertising genres are used in commercials.