Every form of musical theater is based on a combination of musical sound design and a visually represented event on the stage. On principle, musical theater can only be produced as a collective work by several artists. The collaboration of a composer and a librettist already distinguishes musical theater from other musical genres, since the text of a work of musical theater cannot simply be taken from other literary models. The libretto has to be either completely new or an adaptation of a literary model.

Whereas the combination of music and literature as sung text is a constant, and as a rule can be quite precisely notated in a score, the combination of sounds and images has not been subject to any universally accepted standards or methods for notation. The relationship of sounds and images in musical theater is thus, in most cases, only established in a particular performance. Modernism developed integral concepts of musical theater that aimed to bring not only musical elements but also the visual presentation within an overall artistic design, as Wassily Kandinsky’s Der gelbe Klang (The Yellow Sound) and Arnold Schoenberg’s Die glückliche Hand (The Fortunate Hand) demonstrate.

In the postwar avant-gardes, such efforts led to an experimental musical theater that transcended genre and media, in which aspects of indeterminacy, improvisation, and interaction have played a greater role right up to the present.