Harmony
Harmony is the dimension of music concerned with the simultaneous sounding of pitches — what happens when tones overlap in time. A chord is a harmonic event; a chord progression is a harmonic sequence; the sense that music is “going somewhere” and then “arriving” is often a harmonic phenomenon.
Western tonal harmony, codified between roughly 1600 and 1900, organizes chords into functional relationships around a tonic (home key). This system produces the characteristic tension-and-resolution that structures most Western popular and classical music. But this is one harmonic system among many. Harmonic organization in Hindustani raga, in Javanese gamelan, in the parallel organum of medieval Europe, and in the drone-based musics of many traditions operates on fundamentally different principles.
The word “harmony” carries a normative connotation that is worth noting: it implies agreement, concord, things fitting together properly. This connotation has been used ideologically — to naturalize particular social arrangements as “harmonious” and to frame dissonance (musical or social) as disorder. A relational approach to harmony treats consonance and dissonance not as natural categories but as culturally constituted relations: what sounds “resolved” depends on what the listener has learned to expect.