- Diminished 7th chord is a stack of four notes, all a minor third apart.
- There are only three diminished chords to learn: C, A, and D.
- Diminished chords can be used to create tension and release in music.
- Diminished chords can be used to color up dominant chords with extensions and alterations.
- Diminished chords can be used to play a block chord sound.
- Dominant chords are derived from diminished chords.
- Diminished chords can be substituted for dominant chords.
- Diminished chords can be combined with dominant chords to create upper structures.
- Diminished chords can be used to voice major and minor chords.
- Diminished chords can be used in common movements in jazz standards.
via Everything You Need to Know About Diminished Chords