Triads

A triad is a three-note chord built by stacking two thirds. Triads are the building blocks of all Western harmony.

The Four Triad Types

Major (1 - 3 - 5): Built from a major 3rd + minor 3rd. Sounds happy, stable, resolved. C major = C-E-G. Minor (1 - b3 - 5): Built from a minor 3rd + major 3rd. Sounds sad, dark, introspective. C minor = C-Eb-G. Diminished (1 - b3 - b5): Built from two minor 3rds. Sounds tense, unstable, wanting to resolve. C diminished = C-Eb-Gb. Augmented (1 - 3 - #5): Built from two major 3rds. Sounds eerie, suspended, dreamlike. C augmented = C-E-G#.

Diatonic Triads

Harmonizing the major scale in triads produces a fixed pattern of qualities:

This pattern (Maj-min-min-Maj-Maj-min-dim) is the same in every major key.

Triad Function

In functional harmony, triads fill three roles:

• Tonic function (I, iii, vi): Stability and resolution
• Subdominant function (ii, IV): Moderate tension, often moves to dominant
• Dominant function (V, vii°): Maximum tension, pulls toward tonic

The foundational harmonic motion is: Tonic -> Subdominant -> Dominant -> Tonic.

Triads on Guitar

Triads are incredibly powerful on guitar because of their small size. You can voice them on any three adjacent strings, invert them freely, and move them chromatically. In fourths tuning, each triad type has one consistent shape per string group, making them easy to transpose and connect.