The Partitas, BWV 825-830, are a set of six harpsichord suites written by Johann Sebastian Bach, published from 1726 to 1730 as Clavier-Übung I, and the first of his works to be published under his direction. They were, however, among the last of his keyboard suites to be composed, the others being the six English Suites, BWV 806-811 and the six French Suites, BWV 812-817.
The six partitas for keyboard are the last set of suites that Bach composed and the most technically demanding of the three. They were composed between 1725 and 1730 or 1731. As with the French and English Suites, the autograph manuscript of the Partitas is no longer extant.
In keeping with a nineteenth-century naming tradition that labelled Bach's first set of Suites English and the second French, the Partitas are sometimes referred to as the German Suites. This title, however, is a publishing convenience; there is nothing particularly German about the Partitas. In comparison with the two earlier sets of suites, the Partitas are by far the most free-ranging in terms of structure. Unlike the English Suites, for example, wherein each opens with a strict prelude, the Partitas feature a number of different opening styles including an ornamental Overture and a Toccata.
Although each of the Partitas was published separately under the name Clavier-Übung (Keyboard Practice), they were subsequently collected into a single volume in 1731, with the same name, which Bach himself chose to label his Opus 1. Unlike the earlier sets of suites, Bach originally intended to publish seven Partitas, advertising in the Spring of 1730 upon the publication of the fifth Partita that the promised collected volume would contain two more such pieces. The plan was then revised to include a total of eight works: six Partitas in Part I (1731) and two larger works in Part II (1735).
The keys of the six Partitas (B flat major, C minor, A minor, D major, G major, E minor) seem to be an irregular sequence, but in fact they form a sequence of intervals going up and then down by increasing amounts: a second up (B flat to C), a third down (C to A), a fourth up (A to D), a fifth down (D to G), and finally a sixth up (G to E). The key sequence continues into Clavier-Übung II (1735) with two larger works: the Italian Concerto, a seventh down (E to F), and the French Overture, an augmented fourth up (F to B natural). Thus this sequence of customary tonalities for 18th-century keyboard compositions is complete, extending from the first letter of his name (Bach's "home" key, B flat, in German is B) to the last letter of his name (B natural in German is H).
The Overture in the French style, BWV 831, original title Ouvertüre nach Französischer Art, also known as the French Overture and published as the second half of Clavier-Übung II in 1735 (paired with the Italian Concerto), is a suite in B minor for two-manual harpsichord. An earlier version of this work exists, in the key of C minor (BWV 831a); the work was transposed into B minor to complete the cycle of tonalities in Parts One and Two of the Clavier-Übung.
The term overture refers to the fact that this suite starts with an overture movement, and was a common generic name for French suites (his orchestral suites were similarly named). This "overture" movement replaces the allemande found in Bach's other keyboard suites. Also, there are optional dance movements both before and after the Sarabande. Optional movements usually occur only after the sarabande. All three of the optional dance movements are presented in pairs, with the first one repeated (without internal repeats) after the second. Also unusual is the inclusion of an extra movement after the Gigue. This is an "echo", a piece meant to exploit the terraced loud and soft dynamics of the two-manual harpsichord. Other movements also have dynamic indications (piano and forte), which are not often found in keyboard suites of the Baroque period. With eleven movements, the French Overture is the longest keyboard suite ever composed by Bach.
The style of this work refers to composers like François Couperin who had published compositions in this suite format. Such suites had been composed for both solo instruments and for orchestral settings. Bach's composition, though a work for solo harpsichord, employs a fuller sound than was customary for the French composers to whom he referred.