Suspended chords

The third is the note that makes a triad major or minor. A suspended chord removes it and puts a neighbouring note in its place.

• sus4 — the third is replaced by the fourth. Csus4 is C F G.
• sus2 — the third is replaced by the second. Csus2 is C D G.

Neither is major or minor, because neither has a third to decide it. That is the whole effect: the chord sounds open and unsettled, waiting.

Where the name comes from

In classical harmony a suspension is a specific device: a note is held over from the previous chord, creating a dissonance, and then resolves down by step into the note it displaced.

That gives the classic figure — Csus4 falling to C major, with F resolving down to E. The tension is created and then released.

Modern usage is looser. In pop and rock, sus chords are often used as colours in their own right, with no resolution at all. Both uses are legitimate; the second is far more common today.

The two are related

Csus2 is C D G. Gsus4 is G C D. Those are the same three notes.

A sus2 chord is a sus4 chord on a different root — which is worth knowing because it explains why sus chords sound ambiguous. They genuinely are: with no third, the root itself is less clearly defined.

Seventh chords can be suspended too

G7sus4 is G C D F — a dominant seventh with the third replaced. It is a staple of gospel, soul and jazz, and it very often resolves to a plain G7 before the tonic arrives, giving a two-stage release.

Not the same as add chords

• Csus2 = C D G. The third is gone.
• Cadd9 = C E G D. The third is still there, and the second is added above.

They contain a similar tension and sound quite different, because add9 is still unambiguously major. See chord symbols.