The Complete Idiot''s Guide to Music Theory

Definition

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Chapter 10:
Chord Progressions
Unlike the I-IV progression, this one has a bit more finality, thanks to the V-I
relationship. But since you keep going back to the V (and then the I, and then the
V again, and then the I again, and on and on …), it still is very cyclical sounding.
I-IV-V
You can’t get any more popular than the old I-IV-V progression. This is the
progression (in the key of G) you’re playing when you strum the chords G, C,
and D on your guitar.
There are many different variations on the I-IV-V progression. You can leave
out the IV, insert an extra I between the IV and the V, and even tack on another
I-V at the end to wrap things up with a perfect cadence. You also can vary the
number of beats and measures you devote to each chord.
One example of I-IV-V in a four-measure phrase might look like this, in the key
of C:
C / / /
C / / /
F / / /
G / / /
You could also bunch up the IV and the V into a single measure, like this:
C / / /
C / / /
C / / /
F / G /
The progression also could be used over longer phrases, as in this eight-measure
example:
C / / /
C / / /
C / / /
C / / / 
F / / /
F / / /
G / / /
G / / /
The point is these three chords are used in a huge number of modern songs—
and make up the core of what many refer to as “three-chord rock-and-roll.”
They’re not limited to rock, of course; many folk, country, jazz, rap, and even
classical and show tunes are based on these three chords.
It’s an extremely versatile progression.
I-IV-V-IV
This progression is a variation on I-IV-V. The variation comes in the form of a
shift back to the subdominant (IV), which then forms a plagal cadence when it
repeats back to the tonic. In the key of C, the progression looks like this:
C / / /
F / / /
G / / /
F / / /
It’s a nice, rolling progression—not too heavy—without a strong ending feeling to
it—which makes it nice for tunes that repeat the main melody line again and again.
I-V-vi-IV
This progression is another rolling one, good for repeating again and again.
(That’s because of the ending plagal cadence—the IV repeating back to I.)
In the key of C, it looks like this:
C / / /
G / / /
Am / / /
F / / /
135
This progression is
often played with a
dominant seventh
chord on the fifth
(V7), which provides
increased tension before
you return to the tonic.
Tip

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