10.6Minor seventh

Start with C minor:

C E♭ G

Add the minor 7th:

B♭

So:

Cm7 = C E♭ G B♭

Formula:

1 ♭3 5 ♭7

This chord is extremely common in jazz.

Compare:

Cm

with:

Cm7

The 7th softens and enriches the chord.