Power chords are a type of guitar chord commonly used in rock music. Unlike traditional chords that include three or more notes, power chords consist of just two notes: the root note and the perfect fifth. Sometimes the octave of the root is added for a fuller sound, but the chord remains simple and focused.

One reason power chords are so popular in rock is their sonic clarity and strength. Because they omit the third, which defines whether a chord is major or minor, power chords sound neither happy nor sad. This neutrality allows them to fit well with the aggressive, distorted tone typical of rock guitar playing without clashing harmonically.

Additionally, power chords are easy to play and move quickly up and down the neck, making them ideal for fast, energetic riffs and chord progressions. Their simplicity gives guitarists flexibility to combine rhythm and lead elements, which is why you'll often hear them in punk, hard rock, and metal songs.

In short, power chords are foundational to rock music because they deliver a powerful, direct sound that’s simple to execute and harmonically adaptable. This unique combination helps define the driving energy and attitude that rock is known for.