Authentic Cadences are usually two or three chords that lead to a sense of conclusion and resolution in a piece of music. The final chord should therefore be built on the Tonic chord, which is the tonal center of the segment of music being concluded.

Authentic cadences typically follow the pattern V to I or IV - V - I. The V can be replaced with V7, and the IV can be replaced with a II or II7.

Within the category of Authentic Cadences, there are some variations, which depend on how the chords are voiced.

First, we have the Perfect Authentic Cadence.

When the V and I chords are in root position, and the highest voice of the I chord is the same as the root, then we have a Perfect Authentic Cadence.

Next, we have an imperfect Authentic Cadence.

When the highest voice in the I chord is NOT the same as the root, or if either of the two chords is inverted, then we have an Imperfect Authentic Cadence.

A special case of the Imperfect Authentic Cadence is the Evaded Cadence. This occurs when we have a V7 chord in 3rd inversion going to a I chord in 1st inversion. Since the seventh must fall step wise, it forces the cadence to resolve to the less stable first inversion chord. Any chord built on a note other than its root will sound less strong. This is because of the way the harmonics of the root clash with the upper notes in the chord.

Here is an example of how we can use a succession of three cadences to create a gradual build up to the final Perfect Authentic Cadence.

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