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: