Double-stops and power chords
The double-stop is the next step up from single notes. They are used in all kinds of music, from country to heavy metal, and by both lead and rhythm guitarists. Heavy overdriven guitar uses them almost exclusively in the form of power chords.
A double-stop is two notes played at the same time. (This term is exclusive to stringed instruments; for instance, one cannot play a double-stop on a clarinet, while one can play a double-stop on a violin or piano.) Perfect fourths (e.g., C-F) and perfect fifths (e.g., C-G) are the most consonant kind of double-stop, not counting unison and octave double-stops. For this reason, they are often called power chords, especially in the context of overdriven guitar.
This diagram shows the hand positioning for a G5/D power chord:
EADGBE xx00xx 1 ...... 2 ...... 3 ...... 4 ...... 5 ......
The top row shows open strings (shown as the number zero here; non-textual diagrams usually use a circle), and strings which are not played (shown as the letter 'x'). Each row below that indicates a fret (numbered for clarity). However, this diagram has no fretted strings. Therefore, to play this double-stop, simply strike the middle two strings as open.
Here are three fingerings for a G5 power chord:
EADGBE EADGBE EADGBE ---xxx ---xxx ---xxx 1 ...... 1 ...... 1 ...... 2 ...... 2 ...... 2 ...... 3 1..... 3 1..... 3 1..... 4 ...... 4 ...... 4 ...... 5 .34... 5 .33... 5 .44...
These are all the same notes at the same frets, just different fingerings. The numbers indicate the number of finger to use. Finger #1 is the index finger, #2 the middle finger, #3 the ring finger, and finger #4 is the pinky finger. The thumb is not used except while fingerpicking and we will not worry about it yet. To strike this chord, arrange your fingers as shown: index finger on the third fret of the sixth string, and one or two fingers on the fifth fret of the fifth and fourth strings. The second and third fingerings are often more versatile but they are more difficult for the beginner to play. Which fingering is correct depends on both the player and the situation. For now, any fingering will do.
Omitting the sixth string's note makes this the same G5/D chord as before: the strings will have the same pitch. However, it may sound a bit different, because the strings have different tension. In general, the guitar's thinner strings will have a brighter, more ringing sound. The G5 chord is named such because its root (lowest) note is G and its second note, D, is a fifth apart. (Its third note is also G.) The G5/D is called such because it is also a G5 chord, but has D as its bass note. If it were interpreted as a D chord, it might be a D4, following the same logic — however, because it is a kind of suspended chord, it is called a "D suspended fourth", or Dsus4. Which name fits depends entirely upon the context, but its use as a G5/D is far more common.
Now another variation of the G5:
EADGBE --xxxx 1 ...... 2 ...... 3 1..... 4 ...... 5 .3....
Like the G5/D, this double-stop is obtained from removing a note from the full G5 power chord. When played with overdrive, all three of these chords sound remarkably alike, though not identical. Without overdrive they become more distinct.
This is the full G5 chord, although power chords are usually considered to have only two or three notes:
EADGBE --00-- 1 ...... 2 ...... 3 1...22 4 ...... 5 .4....
This is a hard fingering for the beginner and is only given as an example. The A and D strings are in unison, that is, they sound the same note. If the D string were instead fretted at the fifth fret (as in our second example), then the middle two strings would be in unison. Any number of these strings can be omitted, and as long as there are at least two notes, and one is a D and the other a G, it is some kind of G5 chord.