How chords are built: triads

Chords are not random shapes — they are built from a scale with a simple rule: stack thirds. Once you understand this, you can build, name and understand any chord.

The triad

A triad is a three-note chord. Take a scale, start on any note, skip one, take one, skip one, take one:

• From C major (C D E F G A B), start on C, skip D, take E, skip F, take G → C – E – G = C major.

The three notes are called the root (1), the third (3) and the fifth (5).

The four kinds of triads

The size of the thirds decides the chord's quality:

Triad	Formula	Half steps	Example (C)	Sound
Major	1 – 3 – 5	4 + 3	C E G	Bright, happy
Minor	1 – ♭3 – 5	3 + 4	C E♭ G	Dark, sad
Diminished	1 – ♭3 – ♭5	3 + 3	C E♭ G♭	Tense, unstable
Augmented	1 – 3 – ♯5	4 + 4	C E G♯	Mysterious, floating

Hear them:

Major Minor Diminished Augmented

The only difference between major and minor is one note: the third. Lower it by one fret and a happy chord becomes sad.

Triads on the guitar

Guitar chords usually have more than three strings because notes are doubled. Open C (x32010) contains C E G C E — still only three different notes.

You can see a chord's notes anywhere on the neck. Here are all the C major chord tones in the first 12 frets:

Suspended chords

Replace the third with the 2nd or the 4th and you get sus2 and sus4 chords. They are neither major nor minor — they sound open and "suspended", wanting to resolve back to the major chord.

Power chords

Remove the third completely and you get a power chord (5): just root and fifth. Neither happy nor sad — just powerful. That's why it's the sound of rock and metal, which we'll explore in the power chords lesson.