Power chord

A power chord (or fifth chord, written with the suffix "5", e.g. E5) contains only two different notes: the root and its fifth, sometimes doubled with an octave. Unlike a full chord, it has no third — and that absence is exactly what defines it: a power chord sounds neither major nor minor, it's harmonically neutral.

That neutrality is why the power chord became the backbone of rock, punk and metal, especially under distortion: without a third, the chord doesn't produce the harsh clashing harmonics that distortion exaggerates on a full chord.

A consequence rarely explained elsewhere: power chords work with either scale

Because it commits to neither major nor minor, the same power-chord riff can be improvised over with a minor pentatonic scale or its relative major, with no clash from the third. That's exactly the principle behind Guitarshelf's "metal" improvisation sheets: the minor pentatonic sits on top of the power-chord riff with zero conflict, where it would clash against a full major chord.

Guitarshelf's power chords library shows the movable shape across all 12 keys, and the power riff sheet type offers full ready-to-play sequences.