A chord is a collection of musical notes, usually played simultaneously. Chords are defined by their first note (the root) and its relationship to the following notes ( intervals)

Triads

A triad is the most basic type of chord. It consists of 3 intervals (a root, a third, and a fifth). The specific thirds and fifths used determine the type (or quality) of the triad.

Name	Intervals
Major Triad	P1		M3		P5
Minor Triad	P1	m3			P5
Augmented Triad	P1		M3			A5
Diminished Triad	P1	m3		d5

Seventh Chords

A seventh chord is a triad with an additional seventh interval stacked on top.

Name	Intervals
Major 7th	P1		M3			P5				M7
Minor 7th	P1	m3				P5			m7
Dominant 7th	P1		M3			P5			m7
Minor-Major 7th	P1	m3				P5				M7
Diminished 7th	P1	m3			d5			d7
Half-Diminished 7th	P1	m3			d5				m7
Augmented 7th	P1		M3				A5		m7
Augmented Major 7th	P1		M3				A5			M7
Dominant 7th Suspended 4th	P1			P4		P5			m7

Sixth Chords

A sixth chord is a triad with an additional sixth interval stacked on top. They are similar in function to seventh chords.

Name	Intervals
Major 6th	P1				M3			P5		M6
Minor 6th	P1			m3				P5		M6

Suspended Chords

A suspended chord is a like a triad, except it sustitutes a second or fourth interval in place of the third.

Name	Intervals
Suspended 2nd	P1	M2		P5
Dominant 7th Suspended 4th	P1		P4	P5	m7
Suspended 4th	P1		P4	P5

Extended Chords

An extended chord contains extended intervals. [INCOMPLETE]

Name	Intervals
Dominant b9	P1	m2			M3			P5			m7
Dominant 9	P1		M2		M3			P5			m7
Dominant #9	P1			m3	M3			P5			m7
Dominant 11	P1				M3	P4		P5			m7
Dominant #11	P1				M3		d5	P5			m7
Dominant b13	P1				M3			P5	m6		m7
Dominant 13	P1				M3			P5		M6	m7
Minor b9	P1	m2		m3				P5			m7
Minor 9	P1		M2	m3				P5			m7
Minor 11	P1			m3		P4		P5			m7
Minor 13	P1			m3				P5		M6	m7
Major 9	P1		M2		M3			P5				M7
Major 11	P1				M3	P4		P5				M7
Major #11	P1				M3		d5	P5				M7
Major 13	P1				M3			P5		M6		M7

Chords

The foundation of harmony

Triads

Seventh Chords

Sixth Chords

Suspended Chords

Extended Chords