Power chord

In guitar music, a power chord  Play  (also fifth chord) is a chord that consists of the root note and the fifth. Power chords are commonly played on amplified guitars, especially on electric guitar with distortion. Power chords are a key element of many styles of rock and especially heavy metal music.

Analysis

When two or more notes are played through a distortion process that non-linearly transforms the audio signal, additional partials are generated at the sums and differences of the frequencies of the harmonics of those notes (intermodulation distortion).

When a typical chord containing such intervals (for example, a major or minor chord) is played through distortion, the number of different frequencies generated, and the complex ratios between them, can make the resulting sound messy and indistinct. This effect is accentuated as most guitars are tuned based on equal temperament, with the result that minor thirds are narrower, and major thirds wider, than they would be in just intonation.