Musical theater (or musical theatre) is a kind of performance in a theater. A work of musical theater is called a musical. It uses acting, music, songs, and often dance. Some musicals (for example Les Misérables) have only a few lines of dialogue. Everything else is sung. It is usually a mixture of speaking and song. Some well-known musicals are West Side Story, The Sound of Music, Chicago, and Oklahoma!.
Music has been a part of drama since ancient times, but modern Western musical theatre emerged during the 19th century. George M. Cohan is often credited as inventing the musical theatre in America in the early 20th century.