Harmony
Triads and Inversions: Root Position, Sixth, Six-Four
Root position, first and second inversion: how triad voicings shape the bass line, when to invert, and what the figures mean.
Triad
A three-note chord built from a root with a third and a fifth above it. Its quality is major, minor, diminished or augmented.
Also called: Three-note chord
A triad is a chord of three notes stacked in thirds: a root, a third above it and a fifth above that. The quality depends on the intervals. A major triad has a major third and a perfect fifth, as C E G does. A minor triad has a minor third and a perfect fifth, as C E♭ G does. A diminished triad stacks two minor thirds, as in B D F, and an augmented triad stacks two major thirds, as in C E G♯. In a key, the seven diatonic triads are built on the seven scale degrees, and their Roman numerals show how they relate to the tonic. A triad is in root position when the root is in the bass, and inverted when a third or fifth is in the bass instead.
Related terms
- ChordTwo or more pitches sounded together and heard as one unit, usually built in thirds and named by their root and quality.
- Seventh chordA four-note chord made by adding a seventh above the root of a triad. The main types are major, dominant, minor and half-diminished sevenths.
- Root positionA chord arrangement in which the root is the lowest note in the bass, so the chord rests on its fundamental.
- First inversionA triad or seventh chord with its third as the lowest note. A triad in first inversion is written I6 in Roman numerals.
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Harmony
Diatonic Chords in Major and Minor Keys Explained
Diatonic chords are the triads built on each scale degree from the key's own notes. Here are their qualities in major and minor, worked out in C and A.