Five types of seventh chords are commonly used.




A major triad and a minor seventh combine to form a dominant seventh chord. Dominant seventh chords are abbreviated with a simple 7.




A major triad and a major seventh combine to form a major seventh chord.




A minor triad and a minor seventh combine to form a minor seventh chord (m7).




A diminished triad and a diminished seventh combine to form a diminished seventh chord.




Finally, when a diminished triad and a minor seventh combine, a half-diminished seventh chord results.