Rock Opera, A Definition

Rock operas, concept albums, song cycles and oratorios 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 of what constitutes a rock opera. The formal distinction may be that the rock opera tells a coherent (if sometimes sketchy) story, often with first-person lyrics sung by characters; while a concept album or song cycle sets a mood or maintains a theme.