Modes are derived from a parent scale. Any scale can function as this parent scale, but, for practical purposes, our discussion is limited to the modes of the major scale. This is the most common and useful modal structure in western musical theory.
Modes are a hold-over from Ancient Greek musical theory, and, although they are not used very often in classical music, their use in rock, jazz and blues music is indispensable.
The Ancient Greeks had the idea that you could take a parent scale and invert it so that each of the tones of the scale, in turn, would function as the root note. Thus, they could generate seven melodic structures, each having a completely different sound quality as compared to the others, from the same group of notes.
Each of these seven inversions of the scale were associated with the various tribes of Greece and given the name of that tribe.
Keep in mind that each of the seven modes listed above share the same key signature. That is to say, they are all composed of the exact same notes. The only thing that distinguishes one from the next is the fact that you are using a different note within the parent scale as the root.
In order to see the relationship of the seven modes on the guitar, it's helpful to divide the major scale into seven patterns along the length of the fingerboard:
If we change the root note in each successive pattern to match the modal structure it looks like this:
1. C Ionian
2. D Dorian
3. E Phrygian
4. F Lydian
5. G Mixolydian
6. A Aeolian
7. B Locrian
Notice that we are using the exact same patterns, in the exact same order, at the exact same positions on the fingerboard. The only thing that has changed is the note within each pattern that functions as the root. (the squares!!)
