Johann Sebastian Bach (31 March [O.S. 21 March] 1685 – 28 July 1750) 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 Bach family already counted several composers when Johann Sebastian was born as the last child of a city musician, Johann Ambrosius, in Eisenach. After being orphaned at the age of 10, he lived for five years with his eldest brother Johann Christoph, after which he continued his musical education in Lüneburg. From 1703 he was back in Thuringia, working as a musician for Protestant churches in Arnstadt and Mühlhausen and, for longer periods, at courts in Weimar, where he expanded his organ repertory, and Köthen, where he was mostly engaged with chamber music. From 1723, he was employed as Thomaskantor (cantor at St Thomas's) in Leipzig. There, he composed music for the principal Lutheran churches of the city and its university's student ensemble Collegium Musicum. From 1726, he published some of his keyboard and organ music. In Leipzig, as had happened during some of his earlier positions, he had difficult relations with his employer.