A minor

A minor (usually shortened to Am) is a minor scale based on A, which is made up of the pitches A, B, C, D, E, F, G, and A. The harmonic minor scale raises the G to G. Its key signature has no sharps or flats ("see below:" Scales and keys).
Its relative major is C major, and its parallel major is A major. A scale in both A minor and C major can be played on a piano or other keyboard instrument using only the white keys.
Changes needed for the melodic and harmonic versions of the scale are written in with accidentals when needed.
Most of the time key signatures were cancelled whenever the new key signature had fewer sharps or flats than the old key signature, in modern popular music, this is only done when C major or A minor replace another key.