A chord is made from the superposition of two or more intervals having a defined height.

These intervals can be placed in any combination, the most common is the overlap of thirds intervals.

We will have then a series of notes distant from each other in the following order:

- First

- Third

- Fifth

- Seventh

- Ninth

- Eleventh

- Thirteenth

The chords are of two main types: the triads and the tetrad.

A triad is the composition of two third harmonic intervals, and the resulting chord will be constructed with first, third and fifth (1, 3, 5).

A tetrad, is a chord consisting of the superposition of four sounds (1, 3, 5, 7), and is also known as the seventh chord.

The triad is the simplest form of a chord (excluding the power chords) and is divided into four main types:

- Major triad: Tonic, major third and perfect fifth. The note of the triad of the C chord for example, will be (C, E, G)

- Minor triad: Tonic, minor third and perfect fifth. The note of the triad of Cm, for example, will be (C, Eb, G)

- Diminished triad: Tonic, minor third and diminished fifth. The note of the triad of Cdim, for example, will be (C, Eb, Gb)

- Augmented triad: Tonic, major third and augmented fifth. The notes of the triad of Caug, for example, will be (C, E, G #)

Notice that the augmented triad is symmetrical, as it divides the octave into three identical parts.

This means that each of the notes of this triad can be considered as the tonic, outside of the harmonic context in which they are located.

The Caug triad will contain the same notes as Eaug (E, G #, C) and G # aug (G #, C, E).