Chordsthree

Chordsthree is a term used in music theory to describe a simple triadic harmony built from three distinct diatonic chords within a given key. The concept emphasizes economy and clarity of harmony, using exactly three chords to establish and reinforce a tonal center.

Most commonly, chordsthree refers to the I–IV–V triadic sequence in a major key. This set of chords provides a complete tonal cycle: I establishes the key, IV expands the harmony, and V creates tension that resolves back to I. The arrangement can be played in a closed, diatonic texture or expanded with additional voices for richer sonorities. Variations exist that preserve the three-chord constraint while altering color or function. Common substitutions include using the vi or ii in place of IV, or using I–IV–V with added sevenths or suspended chords. In practice, chordsthree is valued for its versatility: it can underpin folk, pop, rock, and traditional harmonies, support melody, and serve as a teaching tool for basic harmonic function and voice leading.

Examples: in C major, the chords C major (I), F major (IV), and G major (V) form a canonical chordsthree progression. In A minor, a three-chord form might be i–iv–V (with V often major via the harmonic minor).

See also: triad, diatonic harmony, cadence, chord progression.