Heptatonic Scale

A heptatonic scale is a musical scale with seven pitches per octave. Among the most famous of these are the major scale, C D E F G A B C; the melodic minor scale, C D E♭ F G A B C ascending, C B♭ A♭ G F E♭ D C descending; the harmonic minor scale, C D E♭ F G A♭ B C; and a scale variously known as the Byzantine, Hungarian, gypsy, or Egyptian scale, C D E♭ F♯ G A♭ B C. South Indian (Carnatic music) classical theory postulates seventy-two melakarta, seven-tone scale types, whereas Hindustani classical music postulates twelve or ten (depending on the theorist) seven-tone scale types collectively called thaat.