A rock opera is a collection of rock music songs with lyrics that relate to a common story. Rock operas are typically 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. These albums are also referred to as “concept albums”.