These four scales are the center-point for much of what transpires in
music on this planet.
   Here's the breakdown of the 7-note "Diatonic" Scales:

MAJOR              1     2      3     4       5       6       7     8(1)

MELODIC MINOR      ............b3....................................

HARMONIC MAJOR     ..................................b6..............

HARMONIC MINOR     ............b3....................b6..............