If you've been in a guitar shop with a good selection of music books, you've no doubt seen a chord dictionary. These handy resources are filled with hundreds–or thousands–of chord shapes of all types, in every key. For players seeking new chordal sounds or who simply want a novel voicing for a workhorse chord like G7, chord dictionaries are great. But if all you really want to do is rock, there's no need for fancy harmonies or knuckle-busting grips. You need a shape that's easy on the fingers and easy on the ears, and that translates anywhere on the fretboard. You need power chords.

What Are Chords?

A little music theory, before we continue. Chords are built from scales. Simple major chords are built from the first (or root), third, and fifth degrees, of a major scale. The C major scale, for example, comprises the notes C, D, E, F, G, A, and B. So, a C major chord contains the notes C, E, and G. To build a minor chord, we use the root, third, and fifth degrees of a minor scale.

At this point, you may be asking yourself, "Hey, if chords have only three notes, how come the standard open-position chord forms use five or six strings?" The answer is redundancy. All three chord tones are present in a standard chord, but one, two, or all three may be duplicated in different octaves. This open chord construction is the norm for guitarists because the shapes are easy to play and they sound good.

There is one more interesting point to note here. Different chords can set very different emotional tones. Major chords, for instance, sound bright or happy, whereas minor chords sound dark and moody. Amazingly, the only difference between the two is in the third degree of the scale. Try this experiment: play an E chord, and then an E minor, as shown below.

What's happening? To make the minor chord, you flatted the third scale degree (from G# to G)—and the whole mood changed! OK, now that you know all about major and minor chords, we can explain what makes power chords so special.

Why Power Chords Rock the World

By comparison with standard chords, power chords are bare-bones structures. They contain just two notes—the root and the fifth. In addition, the root is typically doubled an octave higher to fatten the sound. Absent the third degree, power chords are neither major nor minor, and that's what makes them so useful. In rock music, full-bodied chords may suggest too much, getting in the way of the raw groove. Power chords, instead, just reinforce and fatten up the bass line.

Besides being harmonic chameleons, power chords have other advantages over standard chords. For starters, every one is gripped the same way, so there's no finger tangling when you switch between them. They're also fully mobile across the entire fretboard because they don't use any open strings. Enough theory and explanation! Let's try one.

Here is the simplest possible power chord: E5, built from the notes E (the root) and B (the fifth).

Note that you need only one finger for this one—and that you don't play the top four strings. Here's another E5, this time with a doubled root (voiced E, B, E, low to high).

Now try a fully fingered power chord: G5.

Once you have this chord shape figured out, you have all the power chords in your pocket, since it translates anywhere on the fretboard. The fingering indicates the way most players clutch power chords: index finger on the root (on the low E string), ring finger on the fifth (A string), and pinky on the high octave root (D string).