There are a few different types of cadences:

Perfect authentic cadence-
is when a progression ends with a V-I, whereas the V and I chord are root chords with no inversions, and the I chord has the tonic note doubled in the soprano line.

Imperfect authentic cadence-
Likewise, is when a progression ends with a V-I, but can be inversions and/or there doesn't have to be a doubled tonic note in the soprano line of the I chord.

Half cadence-
is when it ends with a V, hence the "half." Usually it is a root chord, but I guess you could end with an inverted V.

Plagel cadence-
is when it ends with a IV-I chord along with most of the same rules for the PAC. These cadences are the "A-men" of most church plainchants.

Imperfect Plagel cadence-
Like the IAC, but the fact that the VI-I chords can be inverted and such.

The plagel half cadence speaks for itself,
and then there is something called a Picardy 3rd cadence-
which is when you end a major keyed song with a minored tonic. For example: when you are in a piece of C major, and you end with a V-I chord, but the I chord is that of the relative minor key. Kinda weird and rarely used but really cool.

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do you think you can go a little more in depth with this? like explain what cadences are, how they are used and be a little more detailed in your description of the cadences? that would be highly appreciated. thanks

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when you say end in V-I do you meen end with a V chord then a I chord? or end with them at the same time?

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the amen cadence was added to the original chorales by many bishops and such. they were later removed mostly for the preservation of the original piece

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@Demon, it would be a root position V followed by a root position I, with the tonic in the soprano line. (PAC)

@transient, eh? heh, I would think that cadences were part of the original chorale....why would they take the end off of a song to preserve the original? THat doesn't make much sense to me....

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a-men was tacked on at the end of most chorales

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is the tonic, the I chord, or the root note of the I chord?

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It's the latter-tonic is the root of a I chord of the key signature.

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He pretty much went as in depth as one can go when it comes to cadences. There's nothing more anyone can really add.

There's two more cadences that I can think of, and one of them is the deceptive cadence.
The Deceptive Cadence is V- ?. The piece builds up to the V, then when the ear expects to hear the I, it instead goes to another chord, most of the time that chord being a vi.

The other cadence is the leading-tone Imperfect Authentic Cadence. What this is, it's an inverted V7 to I. The other way this can be accomplished is a vii (dim) to I.

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Isn't there also an 'interrupted' and 'imperfect', where are the song sounds like its finishing but then just starts up again or just finishes with an incomplete sound respectively.

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That would be a half cadence. The progression is ? to V. It's pretty much any chord to the V chord.

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Try this:
http://www.dolmetsch.com/musictheory22.htm

OK, but what about songs that just finish without reference to their whereabouts in the key? Like, for example, The Stillborn One by Necrophagist?

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Is that the cadence at the end I'm assuming? Because if it is, then that's a half Cadence. It's ending on an E Major chord, which is the V of A Minor.

EDIT: Sorry, I was thinking about this question once I had left the computer. Now that I look back at the piece you gave me, I believe the last chord before the Cadence could be a iv chord. The part that goes



I believe the chord before the V could be analysed as a D minor chord with the E being a passing tone to the 3rd of the chord.

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