Seventh chords

Seventh chords add a fourth note to the basic triad. Common types:

• Dominant 7 (e.g. G7) — Very common in blues and rock; has a minor seventh.
• Major 7 (e.g. Cmaj7) — Jazz and pop; has a major seventh, sounds smooth.
• Minor 7 (e.g. Am7) — Minor triad plus minor seventh; used in jazz and soul.

Seventh chords make progressions richer and are essential for jazz and many modern styles.