Relative and parallel keys · Keys and key signatures · Music theory
Two relative keys have the same key signature and different tonics: C major and A minor. The relative minor lies a minor 3rd below the major; the relative…
Relative and parallel keys
Two relative keys have the same key signature and different tonics: C major and A minor. The relative minor lies a minor 3rd below the major; the relative major, a minor 3rd above the minor.
Two parallel keys have the same tonic and different modes: C major and C minor. The minor one has three more flats (or three fewer sharps) than its parallel major.
Why these relationships matter
Relative keys share all their notes except the leading tone of the minor, so moving between them is almost invisible: it is the most common modulation in a minor-mode work. Parallel keys share the tonic and very few notes, and their contrast is one of color: going from C major to C minor darkens the sound without changing the center.
Many classical works are organized around these pairs. In the 19th century, chords are also borrowed from the parallel key: in C major, A♭ major or F minor sound like a loan from C minor.