Add chords are a way to make simple major or minor chords sound richer by adding an extra scale degree without changing the basic structure of the chord. Unlike suspended chords, which replace a note, add chords keep all the original chord tones and simply “add” one more for extra color.
For example, a I chord in C major (C, E, G) can become a I(add9) chord by adding the 9th scale degree (D), resulting in C, E, G, and D. In principle, any note can be added to form an add chord. However, the (add9) is by far the most common.
Unlike full ninth chords, which include the seventh scale degree and can thus sound more dissonant, (add9) chords omit this note and consist only of the root, third, fifth, and ninth. These chords, especially when applied to a basic chord with major quality such as IV or V (becoming IV(add9) or V(add9)), result in a rich and pleasing sound. This makes them a common choice in popular music, particularly in genres that aim for a sweet, uplifting quality, such as pop ballads.
“Night Minds” by Missy Higgins is an example of a song that uses the (add9) chord. In this progression, the IV(add9) chord appears right next to the standard IV chord, making it easy to hear the difference the (add9) adds to the sound.
Click on the following songs to see their chords and melody in the TheoryTab database.