Rock opera

Rock operas, concept album, song cycle and oratorio all differ from a conventional rock album, which usually includes songs that are unrelated to each other in terms of storyline. More recent developments include metal opera and rap opera (sometimes also called hip-hopera). The category a particular work falls into is, to some extent, defined by the intent and self-definition of the work by its creator, as long as the creator's interpretation does not stray too far from the accepted definition... full article at wikipedia