One of the two principal modes in modern music (the other being the major mode).
There are three different types of minor scale: "natural", "harmonic", and "melodic", and two types of relationship between minor and major scales: "parallel" and "relative". For purposes of describing the two types of relationship, the "natural minor" will be used.
As for the three varieties of the minor-scale:
The "melodic minor" form contains all of the notes found in all three forms of minor-scale, thus it may be used to illustrate all of the minor-scales in the different keys. Below is a table showing the complete set of melodic-minor scales which occur in standard meantone-based musical notation.
Below is a similar table, this time showing all 31 notes in the standard meantone-based notation on the left (along with their generator numbers, with C as zero), and the scale-degree Roman-numerals in the body of the table. The "natural" form of the minor-scale is composed of the notes which are indicated by lower-case letters (i, ii, iii, iv, v, vi, vii); the "harmonic" and "melodic" forms make use of raised 6th and 7th degrees, which are indicated with capital letters (VI and VII). Horizontal lines separate groups of pitches which have the same accidental (or lack of one), while vertical lines separate the 15 standard keys which have key-signatures (7 with flats, 7 with sharps, and one with neither, plus several others on either end which normally do not have an associated key-signature).
(The reasons for a cardinality of 31 may be found in the discussions of 31edo and 1/4-comma meantone.)
The chord-qualities of the chords on each degree of the harmonic-minor scale are shown below, first for triads then for tetrads; the example is in A-minor:
triads: D C B B A A G# G# G# F F F E E E D D C C B A I II III IV V VI VII m o + m M M o tetrads: F E D D C C B B B A A A G# G# G# G# F F F E E E D D C C B A I II III IV V VI VII m,M7 /o7 +,M7 m7 x7 M7 o7 legend: m minor M major /o half-diminished o diminished x dominant + augmented
The Natural Minor Mode is the tritriadic scale whose Tonic, Subdominant and Dominant triads are Minor Triads (1/1 6/5 3/2) on 1/1, 4/3 and 3/2. The scale 1/1 9/8 6/5 4/3 3/2 8/5 9/5 2/1.
The C or Lydian Octave Species of the P.I.S. whose tetrachords are tuned as 10/9 x 9/8 x 16/15.
The A Mode (Hypodorian) mode of P.I.S. in 12-tone ET or one with close approximation to the Perfect Fifth, i.e., the scale 0 2 3 5 7 8 10 12/0 [in 12-edo degrees].
There are two other common forms of the Minor Mode, the Harmonic Minor whose upper tetrachord is 3/2 8/5 15/8 2/1 and the Melodic Minor with 3/2 5/3 15/8 2/1.
The tonalsoft.com website is almost entirely the work of one person: me, Joe Monzo. Please reward me for my knowledge and effort by choosing your preferred level of financial support. Thank you.