Ok, let's get a bit into modes.
As said, we won't care about others than those deriving from the major scale (maybe later). And as I'm a lazy f*ck, I will at least start the way pretty much everybody starts, namely with the modes of the C major scale (everybody doing so has led to oh-so-funny jokes such as "Hey, please play F dorian" - "But I thought F was lydian..."). I might throw in some other baseline scales for good measure.
Ok, the typical blurb first:
The main idea of modes is being able to grab pretty much each individual note of a major scale and sort of transform it into a tonic (as in "we're home here!") chord.
Note: Parts of that may derive from medieval monks singing and what not, but that's a sort of halfassed thing - but at least the names of the modes are borrowed from that kinda stuff. Just don't make the mistake and look up those monk singing things to translate it into todays meaning of modes.
So, let's take a quick look at our C major scale, goes like:
C, D, E, F, G, A, B
And guess what? Once you can play around with that a bit, you've almost mastered your first mode already. In modal lingo, the major scale is as well known as the "ionian" mode/scale.
Now, before we continue, we need to get a tad more nerdy and analyze that mode. In the end, that's what allows us to distinguish (or rather describe) a mode's character from other mode's characters.
In case of our C major (from now on also known as "ionian") scale, that'd look like (function of note in parenthesis):
C - root (1)
D - major second (2)
E - major third (3+)
F - perfect fourth (4)
G - perfect fifth (5)
A - major sixth (6)
B - major seventh (j7)
Resulting mode: C ionian (also known as major scale)
Note: You might find all sorts of symbols to specify the functions, such as #7 or 7+ for the major seventh. But life is too short to care about that for now.
If we proceed, we can do the same for each note of the scale. So let's do just that:
D - root (1)
E - major second (2)
F - minor third (3-)
G - perfect fourth (4)
A - perfect fifth (5)
B - major sixth (6)
C - minor seventh (7)
Resulting mode: D dorian
E - root (1)
F - minor second (b2)
G - minor third (3-)
A - perfect fourth (4)
B - perfect fifth (5)
C - minor sixth (b6)
D - minor seventh (7)
Resulting mode: E phrygian
F - root (1)
G - major second (2)
A - major third (3+)
B - augmented fourth (#4)
C - perfect fifth (5)
D - major sixth (6)
E - major seventh (j7)
Resulting mode: F lydian
G - root (1)
A - major second (2)
B - major third (3+)
C - perfect fourth (4)
D - perfect fifth (5)
E - major sixth (6)
F - minor seventh (7)
Resulting mode: G mixolydian
A - root (1)
B - major second (2)
C - minor third (3-)
D - perfect fourth (4)
E - perfect fifth (5)
F - minor sixth (b6)
G - minor seventh (7)
Resulting mode: A aeolian (also known as natural minor scale)
B - root (1)
C - minor second (b2)
D - minor third (3-)
E - perfect fourth (4)
F - diminished fifth (b5)
G - minor sixth (b6)
A - minor seventh (7)
Resulting mode: B locrian
Very important note: This is a bone dry posting that I will just leave here as is, serving as a reference. It offers pretty much zero practical value so far.
And to make matters worse: The next posting will likely be just as bone dry again. But after that, things might get interesting.
If anyone has any questions, fire away.