Jazz harmony refers to the system of chords and progressions used in jazz music. It often incorporates extended chords, such as seventh, ninth, and thirteenth chords, which add richness and complexity. Jazz musicians frequently use substitutions and alterations to create unique sounds, allowing for greater expression and improvisation. In jazz, harmony is not just a backdrop; it plays a crucial role in shaping the music's emotional and dynamic qualities. Musicians often employ techniques like modal interchange and chromaticism to enhance their harmonic vocabulary, making jazz a distinctive and evolving genre that encourages creativity and exploration.