A rock opera is a collection of rock music songs with lyrics that relate to a common story. Rock operas typically are released as concept albums and are not scripted for acting, which distinguishes them from operas, although several have been adapted as rock musicals. The use of various character roles within the song lyrics is a common storytelling device. The success of the rock opera genre has inspired similar works in other musical styles, such as rap opera.
In an early use of the term, the July 4, 1966, edition of RPM Magazine (published in Toronto) reported that "Bruce Cockburn and Mr [William] Hawkins are working on a Rock Opera, operating on the premise that to write you need only 'something to say'."
Colin Fleming of The Atlantic has identified The Story of Simon Simopath (1967) by British psychedelic band Nirvana as the first recorded rock opera. Later in 1967, Montreal's Influence recorded a long suite titled "Mad Birds of Prey (A Mini-Opera)", which closed out their sole album, which was released in January 1968. Nevertheless, Neil Strauss of The New York Times wrote that S.F. Sorrow (1968) by The Pretty Things is "generally acknowledged as the first rock opera." Although Pete Townshend denied taking any influence from S.F. Sorrow, critics have compared The Who's Tommy to it. Scott Mervis of the Pittsburgh Post-Gazette wrote that, although Tommy was not the first rock opera, it was the first album to be billed as such. Tommy would go on to influence On and On, a rap opera by The Fat Boys and American Idiot, a punk rock opera by Green Day. In an effort to appeal to more modern audiences, opera companies have welcomed more pop and rock influences. The resulting rock operas have met varying degrees of success as the worlds of high art and low art mix. Other notable rock operas include The Who's Quadrophenia in 1973 and Pink Floyd's The Wall in 1979.
In Russian music, the term zong-opera (Зонг-опера) is sometimes used, since the first Soviet-Russian rock-opera Orpheus and Eurydice was described with this term for political reasons. While the term "rock-opera" was already known in the Soviet rock music circles, the term "rock" was blacklisted by the Soviet Ministry of Culture. Therefore, the term "zong" was used, a Russian-language rendering of the German word "Song", borrowed from German for philosophical Songs embedded in the dramaturgy of Bertold Brecht, officially popularized in the Soviet Union.
According to Fleming, rock operas are more akin to a cantata or suite, as they are not usually acted out. Similarly, Andrew Clements of The Guardian called Tommy a subversively-labeled musical. Clements states that lyrics drive rock operas, which makes them not a true form of opera. Responding to accusations that rock operas are pretentious and overblown, Pete Townshend wrote that pop music by its very nature deflates such attitudes and is simplistic. Townshend said that the only goal of pop music is to reach audiences, and rock operas are merely one more way to do so. Peter Kiesewalter, on the other hand, said that rock music and opera are "both overblown, massive spectacles" that cover the same themes. Kiesewalter, who was originally not a fan of opera, did not think the two styles would mix well together, but his modernized operas with rock music surprised him with their popularity at the East Village Opera Company.
Rock operas are usually recorded and performed on albums by the artists themselves, but they can also be performed on the stage, such as Rent, which played on Broadway. This usage has also courted controversy; Anne Midgette of The New York Times called them musicals with "no more than the addition of a keyboard and a drum set."