A staple of metal music, the power chord is a simple diad notable for its ease of play and flexible utility. Playable with two fingers, or as little as one with the use of drop-tuning, the power chord can maintain its distinct sound at high levels of distortion, making it ideal for hard rock and metal guitarists.
Breaking it down: What is a power chord?[]
Simply put, a power chord is not a true chord, but a diad; a set of two notes. A typical power chord consists of the root note of a scale and its perfect fifth. When you hear a growling roar-like chord, this is typically what you're hearing. An additional note, a full octave above the root, can also be added to "fill out the sound."
Alternatively, a fourth can be substituted for the fifth. These typically sound better on the higher strings of the guitar, but can be used anywhere the standard fifth can be found. To hear the sharp, cobra-like strike of these fourths, listen to the opening riff of Deep Purple's "Smoke on the Water", Ted Nugent's "Cat Scratch Fever," or Dio's "Stand up and shout."
Tell me more, sir: The Advantages of the Power Chord[]
Since the third is a necessary component in determining the Major (happy) or Minor (Sad) nature of a scale, a power chord's lack of a third makes it neither major nor minor. This means that regardless of the mood a song is meant to convey, a power chord will not conflict with it. Also, power chords do not require the use of any open notes, making them fully movable to virtually any postion on the fretboard. Finally, as discussed earlier, power chords maintain a pleasing sound even at extremely high levels of distortion. These factors make the power chord ideal for the high volume and frantic speeds of metal music.