Harmony, in music, is the sound of two or more notes heard simultaneously.
Melody and rhythm can exist without harmony.
The greatest part of the world’s music is nonharmonic. Many musical styles consist basically of unharmonized melodic lines and their rhythmic organization. Harmony in the Western sense is a comparatively recent invention. Harmony
Chords are three or more single pitches that are heard simultaneously.
Video completo en: El Diario de la Música