Johann Sebastian Bach was a German composer and musician of the late Baroque period. He is known for his prolific authorship of music across a variety of instruments and forms, including; orchestral music such as the Brandenburg Concertos; solo instrumental works such as the cello suites and sonatas and partitas for solo violin; keyboard works such as the Goldberg Variations and The Well-Tempered Clavier; organ works such as the Schubler Chorales and the Toccata and Fugue in D minor; and choral works such as the St Matthew Passion and the Mass in B minor. Since the 19th-century Bach Revival, he has been generally regarded as one of the greatest composers in the history of Western music.

The Well-Tempered Clavier, BWV 846–893, consists of two sets of preludes and fugues in all 24 major and minor keys for keyboard by Johann Sebastian Bach. In the composer's time, clavier referred to a variety of stringed keyboard instruments, most typically the harpsichord or clavichord, but not excluding the organ, although it is not a stringed keyboard.