Now listen, I'm not gonna take the time to type out all the mode shapes, patterns, boxes, whatever you wanna call them. If you haven't learned those already (even though they're just the major scale spread out over the entire fret board) then go look at one of the other mode lessons on here and come back to this later.
Alright, here we go... First of all I'm gonna give you the names of all the modes.
The Wrong WayG Ionian (Major) (G, A, B, C, D, E, F#, G) (1, 2, 3, 4, 5, 6, 7, 1)
A Dorian (minor) (A, B, C, D, E, F#, G, A) (2, 3, 4, 5, 6, 7, 1, 2)
B Phrygian (minor) (B, C, D, E, F#, G, A, B) (3, 4, 5, 6, 7, 1, 2, 3)
C Lydian (Major) (C, D, E, F#, G, A, B, C) (4, 5, 6, 7, 1, 2, 3, 4)
D Mixolydian (Major) (D, E, F#, G, A, B, C, D) (5, 6, 7, 1, 2, 3, 4, 5)
E Aeolian (minor) (E, F#, G, A, B, C, D, E) (6, 7, 1, 2, 3, 4, 5, 6)
F# Locrian (diminished) (F#, G, A, B, C, D, E, F#) (7, 1, 2, 3, 4, 5, 6, 7)
See what I mean? Every one of these has the exact same notes, because they are all the exact same scale. Let me clarify something real quick before I make my version of this list... The list of modes I just gave you is not really wrong per se, it's just that most guitarists see that and think something like "So if I have a chord progression of G major, A minor, and E minor and I wanna play modally over it, I would play G Ionan, A Dorian, and E Aeolian." That's what's wrong with, and what I hate, about all the other lessons I've seen, they lead people to believe that modes are just a fancy way to refer to chunks of the major scale.
Here's What Makes Modes DifferentG Ionian (Major) (G, A, B, C, D, E, F#, G) (1, 2, 3, 4, 5, 6, 7, 1)
G Dorian (minor) (G, A, Bb, C, D, E, F, G) (1, 2, b3, 4, 5, 6, b7, 1)
G Phrygian (minor) (G, Ab, Bb, C, D, Eb, F, G) (1, b2, b3, 4, 5, b6, b7, 1)
G Lydian (Major) (G, A, B, C#, D, E, F#, G) (1, 2, 3, #4, 5, 6, 7, 1)
G Mixolydian (Major) (G, A, B, C, D, E, F, G) (1, 2, 3, 4, 5, 6, b7, 1)
G Aeolian (minor) (G, A, Bb, C, D, Eb, F, G) (1, 2, b3, 4, 5, b6, b7, 1)
G Locrian (diminished) (G, Ab, Bb, C, Db, Eb, F, G) (1, b2, b3, 4, b5, b6, b7, 1)
This is how you should see modes. Notice how if you base them all off G the differences between them become very apparent.
Now for the easy part. I'm now going to tell you how to use them... Let's say for example, you have the same chord progression as earlier (GM, Am, and Em) just three simple triads. Now, you could always just play it safe and noodle around with the G major scale for the entire progression, or you could play your newly learned modes!
Let me show you chord by chord.
For the GM chord, you could use any major mode (with G as the tonic of course). So, you could play G Ionian, G Lydian, G Mixolydian, or even some strange combination of the three over your GM chord.
For the Am chord, you could use any minor mode (this time using A as your tonic). So, you could play A Dorian, A Phrygian, A Aeolian, or combine the three in various ways over your Am chord.
The Em chord would work exactly like the Am did, except you would use E Dorian, Phrygian, and Aeolian instead of A.
If your wondering about Locrian, it goes with diminished chords and that's it, so if we had an F# diminished chord in our progression than you would just play F# Locrian. It gets better! If you're just using power chords (which aren't defined as major or minor) you can use any of the major or minor modes you want!
However, the more intricate the chords you use (using 7ths, 9ths, etc.) the less options you have on what modes you use, because you have to make sure the notes of the chord match with the notes of the mode. For instance, if you played a GM chord with a flat 7th, then you would need to play G Mixolydian would be your most likely choice of mode because it is Major and has a flat 7th. Get it?
Well, this is all I can think of to try to explain modes... It's kinda hard to explain without being able to sit in front of someone with a guitar and just show them haha. I hope this helps anyone out there confused about modes and why you should learn them.