The term mode is another name for a scale. There are seven different modes which can be derived from the major scale by starting on each of the seven notes of the major scale. These modes were first used in ancient Greece and have been widely used throughout history in all types of music. They are particularly useful for improvising or composing melodies over chord progressions.
1. Ionian mode -The Ionian mode is another name for the major scale itself. By starting and ending on the first note of the major scale (C) you can play the Ionian mode.
2. Dorian mode - Starts and ends on the second note of the major scale (in this case D).
3. Phrygian mode - Starts and ends on the third note of the major scale (in this case E).
4. Lydian mode - Starts and ends on the fourth note of the major scale (in this case F).
5. Mixolydian mode - Starts and ends on the fifth note of the major scale (in this case G).
6. Aeolian mode - Starts and ends on the sixth note of the major scale (in this case A).
7. Locrian mode - Starts and ends on the seventh note of the major scale (in this case B).
Here are the seven modes derived from the C major scale played against the seven scale tone seventh chords from the key of C major.
Because each seventh chord contains four notes of the mode it relates to, modes work extremely well over seventh chords. Listen to the sound of this line using the D Dorian mode over a Dm7 chord. Learn this line in the open position and then move it through all five forms on the fretboard. Experiment with all the modes over the various types of seventh chords from the key of C major until you can easily recognise the sound of each mode and know which chord it works best over.