The Complete Idiot''s Guide to Music Theory

Part 3:
Tunes
134
This type of ending progression is called an 
imperfect cadence,
and you can get to
the V chord any number of ways—I-V, ii-V, IV-V, and vi-V being the most
common. In the key of C, these progressions look like this:
I-V:
C / / /
G / / /
ii-V:
Dm / / /
G / / /
IV-V:
F / / /
G / / /
vi-V:
Am / / /
G / / /
Interrupted Cadence
Even less final than an imperfect cadence is an ending progression called an
interrupted cadence.
In this progression, you use a V chord to trick the listener
into thinking a perfect cadence is on its way, but then move to any type of
chord 
except
the tonic.
V-IV, V-vi, V-ii, and V-V7 progressions all are interrupted cadences—and, in
the key of C, look like this:
V-IV:
G / / /
F / / /
V-vi:
G / / /
Am / / /
V-ii:
G / / /
Dm / / /
V-V7:
G / / /
G7 / / /
Common Chord Progressions
Given everything you’ve learned about chord leading and cadences, you should
be able to create your own musically sound chord progressions. However, just
in case you get stuck, let’s take a look at some of the most popular chord pro-
gressions used in music today.
I-IV
It doesn’t get much simpler than this, just the tonic (I) and the subdominant
(IV) chords repeating back and forth, over and over. This is a cyclical progres-
sion, good for songs that don’t really have a final resolution point.
In the key of C, the progression looks like this:
C / / /
F / / /
I-V
If you can cycle between the tonic and the subdominant (IV), why not the tonic
and the dominant (V)? Like the first progression, the simplicity of this one
makes it quite common in folk and some forms of popular music.
In the key of C, the progression looks like this:
C / / /
G / / /
In classical music theory,
an interrupted cadence 
is more often called a
deceptive cadence.
Note
Jazz musicians
sometimes refer to chord
progressions as chord
changes
—as in, “Dig
those crazy changes, man!”