The term functional harmony defines the gravitational harmonic tendencies found within the major-minor tonal system. Functional harmony uses terms that clarify additional understandings about the major-minor tonal system. Harmony that limits itself to the seven tones of a scale is known as diatonic harmony . Harmony that admits additional tones beyond the basic seven-tone scale is known as chromatic harmony . It is mostly the harmonic materials of a musical passage that accomplishes modulation and indicates modulation to the ear.
Harmony contributes to the effect of motion in music.
Since harmony is derived from scale pitches, harmony automatically assumes the gravitational properties that scales display. The gravitational attraction of scale pitches impart goal-oriented motion to the effect of harmonic progressions that are designed with this gravitational effect in mind. Chords that move by root movement up an interval of a fourth, down a fifth, down a third or up a second, give a strong sense of goal oriented motion to passages of music. Since rhythm is also an integral part of harmonic accompaniment, harmonic progressions contribute a strong and sustained sense of movement to music. Harmony contributes to the structural design of music.