Harmonic minor keys are used when writing chords. There is another version of the minor key known as the melodic minor. This is used when writing a melody. Each key signature has two possible keys.

If you look at a music or piano keyboard ... Of course, not all triads have to be chords of C major or minor. You can use the process, of selecting the 1st (root), 3rd, and 5th degree of either ...