Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In music, a power chord is a chord consisting of only the root note of the chord and the fifth, usually played on electric guitar, and typically through an amplification process that imparts distortion. Power chords are a key element of many styles of rock music. When two or more notes are played through a distortion process which non-linearly transforms the audio signal, additional harmonics are generated at the sums and differences of the frequencies of the harmonics of those notes.