Major / Minor Modes
Modes can have a major or minor sound, based on the third note in the mode.
Some modes have a major third (3) and are good to use while improvising over a major chord or key. Some modes have a minor third (b3) and are good to use while improvising over a minor chord or key.
Major Modes - Ionian, Lydian, Mixolydian
Minor Modes - Dorian, Phrygian, Aeolian
Diminished Mode - Locrian
The 7th mode, Locrian, is special in that it has a b3 and b5, which technically makes it not minor but diminished. For the sake of this lesson, relating to major and minor, we will mostly ignore Locrian.