Jazz harmony is the
theory and practice of how
chords are used in
jazz music. Jazz bears certain similarities to other practices in the tradition of Western
harmony, such as many
chord progressions, and the incorporation of the
major and minor scales as a basis for chordal construction. In jazz, chords are often arranged vertically in
major or
minor thirds, although
stacked fourths are also quite common. Also, jazz music tends to favor certain harmonic progressions and includes the addition of
tensions,
intervals such as 9ths, 11ths, and 13ths to chords. Additionally,
scales unique to style are used as the basis of many harmonic elements found in jazz. Jazz harmony is notable for the use of
seventh chords as the basic harmonic unit more often than
triads, as in
classical music. In the words of Robert Rawlins and Nor Eddine Bahha, "7th chords provide the building blocks of jazz harmony."