prelude

In music, a composition intended as the preface to further music, especially preceding a fugue, forming the opening piece of a suite, or setting the mood for a stage work, as in Richard Wagner's Lohengrin. As used by Frédéric Chopin, a prelude is a short self-contained piano work.

A prelude is often rhetorical in style, mixing fast runs and sustained chords. It thereby allows the musicians to form an aural picture of the sound quality of the auditorium. In orchestra concerts the overture fulfils a similar role.