Reference

Cadence

A chord progression at the end of a phrase. There are several type of cadences.

The perfect authentic cadence. V (dominant) - I (tonic). Both chords must be in root position and the uppermost note in the tonic chord must be the tonic:

The Imperfect authentic cadence. V - I like the perfect authentic cadence but one of the chords is inverted or the uppermost note in the tonic chord is not the tonic. Two examples:

Imperfect because both chords are inverted.

Imperfect because the tonic chord uppermost note is not the tonic.

Half cadence or semi cadence. A chord progression that ends in the V (dominant):

Deceptive or interrupted cadence. V (dominant) - vi or V - IV:

Plagal cadence. IV (subdominant) - I: