Songs which are written in a minor key contain notes and chords from a minor scale. There are several different kinds of minor scales, but only one type of minor key. The two most important types of minor scales are the natural minor scale and the harmonic minor scale.
The harmonic minor scale differs from the natural minor scale in that its seventh note is raised by one semitone, creating a snake charmer sound. In the A harmonic minor scale, the raised seventh note is G#.