The two main categories in tonality are major and minor. The single determining factor of what makes a chord major or minor is the third.

• When the third is two wholetones (4 frets) above the root note the chord or scale is major.

• When the third is one and a half tones (3 frets) above the root note the chord or scale is minor.

D major (root note is D, third note of scale is F#).

D minor (root note is D, flattened third note of scale is F).

Some chords such as guitar power chords are neither major or minor because the third isn’t played.

Power chord

Major chords are often described as happy and minor chords as sad but there is a whole range of emotion in between these two extremes. Refer to the section on modes to hear how the Ionian mode sounds happier than the Mixolydian and how the Locrian mode sounds sadder than the Dorian.