Within the Fretboard Knowledge domain, we loosely define chords as "three or more pitched sounds played simultaneously".

In Western music theory, common chords are generally built by stacking minor and major third intervals.In Fretboard Knowledge, "common chords" means our list of all strict and non-strict triads and seventh chords.

Strict triads and seventh chords are the chords obtained by stacking three or four minor or major thirds and thus have the tone-functions prime, third, fifth (and seventh).

Non-strict triads and seventh chords are chords where these intervals have been suspended or augmented in such a way that the interval-stack does not consist of only minor and major third intervals.

There are four strict triads, meaning that these are constructed by stacking notes in intervals of thirds:

There are six seventh chords that confirm to the principle of stacking thirds.

Three more seventh chords are relevant but these are not conceived by strictly stacking intervals of a third, but they all have definate alterations of the essential chordtones.