What does “extended chords” refer to in jazz music?

In jazz music, the term "extended chords" refers to chords that include additional notes beyond the basic triad or standard four-note seventh chord. This can include adding the ninth, eleventh, or thirteenth notes of the scale to these chords, creating a richer, more complex harmonic structure. Extended chords enhance the tonal color and emotional depth of music, allowing for greater expressiveness in performances.

These added notes are essential in jazz, as they support the improvisational nature of the genre, providing more options for soloists and accompanists alike. By stacking these additional tones, musicians are able to create sophisticated and varied harmonic landscapes that are characteristic of jazz music.