The Prelude in C Major, BWV 846, is a piano composition written by Johann Sebastian Bach. It is the first piece in the first book of The Well-Tempered Clavier, a series of 48 preludes and fugues by the composer. The prelude is 35 bars long and consists mostly of broken chords. It has a simple and elegant structure, characterized by a continuous flow of eighth notes in a harmonic pattern. The prelude modulates through various related keys, such as G major, D minor, A minor, and F major, before returning to the home key of C major. The prelude ends with a single C major chord.