A prelude (German: Präludium or Vorspiel; Latin: praeludium; French: prélude; Italian: preludio) is a short piece of music, the form of which may vary from piece to piece. The prelude may 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 also may refer to an overture, particularly to those seen in an opera or an oratorio.
The first preludes to be notated were organ pieces that were played to introduce church music, the earliest surviving examples being five brief praeambula in the Ileborgh Tablature of 1448. These were closely followed by freely composed preludes in an extemporary style for the lute and other Renaissance string instruments, which were originally used for warming up the fingers and checking the instrument's tuning and sound quality, as in a group of pieces by Joan Ambrosio Dalza published in 1508 under the heading tastar de corde (in Italian, literally, "testing of the strings").
Keyboard preludes started appearing in the 17th century in France: unmeasured preludes, in which the duration of each note is left to the performer, were used as introductory movements in harpsichord suites. Louis Couperin (c.1626-1661) was the first composer to embrace the genre, and harpsichord preludes were used until the first half of the 18th century by numerous composers including Jean-Henri d'Anglebert (1629-1691), Élisabeth Jacquet de la Guerre (1665-1729), François Couperin (1668-1733) and Jean-Philippe Rameau (1683-1764), whose very first printed piece (1706) was in this form. The last unmeasured preludes for harpsichord date from the 1720s.
The development of the prelude in 17th century Germany led to a sectional form similar to keyboard toccatas by Johann Jakob Froberger or Girolamo Frescobaldi. Preludes by northern German composers such as Dieterich Buxtehude (c.1637-1707) and Nikolaus Bruhns (c.1665-1697) combined sections of free improvised passages with parts in strict contrapuntal writing (usually brief fugues). Outside Germany, Abraham van den Kerckhoven (c.1618-c.1701), one of the most important Dutch composers of the period, used this model for some of his preludes. Southern and central German composers did not follow the sectional model and their preludes remained improvisational in character with little or no strict counterpoint.
During the second half of the 17th century, German composers started pairing preludes (or sometimes toccatas) with fugues in the same key; Johann Pachelbel (c.1653-1706) was one of the first to do so, although Johann Sebastian Bach's (1685-1750) "prelude and fugue" pieces are much more numerous and well-known today. Bach's organ preludes are quite diverse, drawing on both southern and northern German influences. Most of Bach's preludes were written in the theme and variation form, using the same theme motif with imitation, inversion, modulation, or retrograde the theme as well as other techniques involved in this baroque form.
Johann Caspar Ferdinand Fischer was one of the first German composers to bring the late 17th-century French style to German harpsichord music, replacing the standard French ouverture with an unmeasured prelude. Fischer's Ariadne musica is a cycle of keyboard music which consists of pairs of preludes and fugues; the preludes are quite varied and do not conform to any particular model. Ariadne musica served as a precursor to Johann Sebastian Bach's The Well-Tempered Clavier, two books of 24 "prelude and fugue" pairs each. Bach's preludes were also varied, some akin to Baroque dances, others being two- and three-part contrapuntal works not unlike his inventions and sinfonias. Bach also composed preludes to introduce each of his English Suites.
The Well-Tempered Clavier influenced many composers in the coming centuries, some of whom wrote preludes in sets of 12 or 24, sometimes with the intention of utilizing all 24 major and minor keys as Bach had done. Frédéric Chopin (1810-1849) wrote a set of 24 preludes, Op. 28, often composed in a simple ternary form, which liberated the prelude from its original introductory purpose and allowed it to serve as an independent concert piece. While other pianist-composers, including Muzio Clementi, Johann Nepomuk Hummel and Ignaz Moscheles, had previously published collections of preludes for the benefit of pianists unskilled at improvisatory preluding, Chopin's set renewed the genre.
Chopin's set served as a model for other collections of 24 or 25 piano preludes in the major and minor keys, including those by Charles-Valentin Alkan (Op. 31 for piano or organ), Ferrucio Busoni (Op. 37, BV 181), César Cui (Op. 64), Stephen Heller (Op. 81), and Alexander Scriabin (Op. 11). Claude Debussy (1862-1918) wrote two books of impressionistic piano preludes which, unusually in this genre, carry descriptive titles. Chopin's conception of the prelude as an unattached character piece expressing a mood rather than a specific musical programme extended into the 20th century with works by composers such as George Antheil, George Gershwin, Alberto Ginastera, Dmitry Kabalevsky, Bohuslav Martin?, Olivier Messiaen, Sergei Rachmaninoff (who also completed an entire set), Giacinto Scelsi and Karol Szymanowski.
Preludes were also incorporated by some 20th-century composers into Baroque-inspired suites: such "attached" preludes include Maurice Ravel's Le tombeau de Couperin (1914/17) and Arnold Schoenberg's Suite for piano, Op. 25 (1921/23), both of which begin with an introductory prelude (Schoenberg's choral introduction to the Genesis Suite is a rare case of an attached prelude written in the 20th century without any neo-baroque intent). As well as a series of unattached piano preludes (Op. 2), Dmitri Shostakovich composed a set of 24 Preludes and Fugues in the tradition of Bach's The Well Tempered Clavier.
Some avant-garde composers have also produced unattached preludes. John Cage's brief Prelude for Meditation is written for prepared piano, while François-Bernard Mâche's Prélude (1959) and Branimir Saka?'s Aleatory Prelude (1961) call on electronic resources and aleatoric techniques.