The Rock Opera is a specific type of rock Concept Album which tells a story. The "opera"-ness of the form varies significantly. Some are sung entirely from the point of view of a single (possibly unnamed) character, while others have explicitly-named characters interacting with each other in song (and likely performed by different singers). The Other Wiki's entry for Tommy suggests that "rock cantata" or "rock song cycle" might be a more accurate term, since a rock opera is purely a musical performance that is not intended to be staged or acted out. This is odd, since Tommy was the first widely heard Rock Opera, and was farther on the opera side of this scale.