A prelude is a short piece of music, the form of which may vary from piece to piece. The prelude can be thought of as a preface. While, during the Baroque era, for example, it may have served as an introduction to succeeding movements of a work that were usually longer and more complex, it may also have been a stand alone piece of work during the Romantic era. It generally features a small number of rhythmic and melodic motifs that recur through the piece. Stylistically, the prelude is improvisatory in nature. The prelude can also refer to an overture, particularly to those seen in an opera or an oratorio.
Bach: The Well-Tempered Clavier
BWV 846-903, Books I & II
48 Preludes & Fugues
Glenn Gould, piano