Chords

In music theory, a chord is a group of three or more notes played simultaneously. The most common chords, called triads, consist of a root note, a third above the root, and a fifth above the root. Triads form the basic building blocks of harmony in much of Western music.

Triads come in several qualities: major triad (root, major third, perfect fifth); minor triad (root, minor third, perfect fifth); diminished triad (root, minor third, diminished fifth); augmented triad (root, major third, augmented fifth). Inversions place different chord tones in the bass: root position, first inversion, second inversion. These inversions can affect the chord’s sound and its voice-leading.

Seventh chords add a seventh above the root, giving longer-lasting and more complex harmony. Common varieties include major seventh, minor seventh, dominant seventh, half-diminished seventh, and fully diminished seventh. Chords are built by stacking thirds and are notated by quality and root (for example C, Cm, C7, Cmaj7). Extensions include ninths, elevenths, and thirteenths, which add further tones above the seventh.

In tonal music, chords generally serve functional roles: the tonic suggests rest, the subdominant prepares movement, and the dominant creates tension that resolves to the tonic. This results in common progressions such as I–IV–V–I. In jazz and popular music, extended and altered chords expand color and texture, while in other traditions harmony may be less central.

Chords can be represented in notation with symbols above the staff or with Roman numerals in analysis. They are a central concept in Western harmony but vary in importance across musical cultures, where melody and rhythm may carry the musical idea with fewer harmonic layers.