Original: While this definition encompasses many scales and modes such as Dorian mode and the Phrygian mode , the term in its stricter sense is usually limited to the natural minor , harmonic minor , and melodic minor scales , described below , which are in most common use in Western classical music ( see major and minor ) .
Simplified: One way the harmonic minor is different to the natural minor is that it has two chords which have the same structure when inverted , so they do not belong to any key .