A major chord consists of a root, a major third, and a perfect fifth.

A major chord is constructed by stacking a major third on top of the root, and then a perfect fifth on top of the major third.

C major is a major chord because it consists of the notes C, E, and G, which form a major third and a perfect fifth.

The relative minor of a major key is the minor key that shares the same key signature. In the case of C major, the relative minor is A minor.

A minor chord consists of a root, a minor third, and a perfect fifth.

A minor chord is constructed by stacking a minor third on top of the root, and then a perfect fifth on top of the minor third.

G minor is a minor chord because it consists of the notes G, B♭, and D, which form a minor third and a perfect fifth.

The relative major of a minor key is the major key that shares the same key signature. In the case of A minor, the relative major is C major.

A chord cannot be both major and minor at the same time.

A diminished chord consists of a root, a minor third, and a diminished fifth.

A diminished chord is constructed by stacking a minor third on top of the root, and then a diminished fifth on top of the minor third.

An augmented chord consists of a root, a major third, and an augmented fifth.

An augmented chord is constructed by stacking a major third on top of the root, and then an augmented fifth on top of the major third.

A suspended chord is a chord that omits the third and replaces it with another note, usually the fourth or the second.

A suspended fourth chord is constructed by stacking a perfect fourth on top of the root, and then a perfect fifth on top of the perfect fourth.