In music, a chorale prelude is a short liturgical composition for organ using a chorale tune as its basis. It was a predominant form of the German Baroque era and reached its culmination in the works of J.S. Bach, who wrote 46 (with a 47 unfinished) examples of the form in his Orgelbüchlein. The Casavant pipe organ at Notre-Dame de Montréal Basilica, Montreal The organ is one of the oldest musical instruments in the western musical tradition, with a rich history connected with the Christian religion and civic ceremony. ... A chorale is a hymn of the Lutheran church sung by the entire congregation. ... Baroque music describes an era and a set of styles of European classical music which were in widespread use between approximately 1600 to 1750 (see Dates of classical music eras for a discussion of the problems inherent in defining the beginning and end points). ... Johann Sebastian Bach (21 March 1685 O.S. – 28 July 1750 N.S.) was a German composer and organist whose sacred and secular works for choir, orchestra and solo instruments drew together almost all of the strands of the baroque style and brought it to its ultimate maturity. ... Orgelbüchlein: Written during one of Bachs more productive periods of 1708–14, The Orgelbüchlein (or Little organ book), is a set of 45 Chorale preludes written for organ. ...

The liturgical function of a chorale prelude was to introduce the hymn about to be sung by the congregation, usually in a Protestant, and originally in a Lutheran, church. Although it was typically a polyphonic setting, the melody would be plainly audible. There was sometimes an obbligato line above or below the melody. Protestantism is a general grouping of denominations within Christianity. ... The Lutheran movement is a group of denominations of Protestant Christianity by the original definition. ... In music, the word texture is often used in a rather vague way in reference to the overall sound of a piece of music. ... Italian for obligatory, from Latin word obligare, to oblige. ...

As an independent genre, the chorale prelude began with the works of Dieterich Buxtehude, who wrote 30. Numerous examples also exist from the 19th and 20th centuries, including some by Johannes Brahms and Max Reger. Works in the form continue to be composed in the present day. Buxtehude Dieterich Buxtehude (Dietrich, Diderich) (ca. ... Johannes Brahms Johannes Brahms (May 7, 1833 – April 3, 1897) was a German composer of Romantic music, who predominantly lived in Vienna, Austria. ... Johann Baptist Joseph Maximilian Reger (March 19, 1873 – May 11, 1916) was a German composer, organist, pianist and teacher. ...