Just to add to what Benoit said, and because most guitar players are weak in music theory (myself included), a power chord really isn't a chord, given there's only 2 notes. A power chord is really only an interval, missing the 3rd- the 3rd gives a chord the major or minor "flavor". Lots of classically trained players put down power chords, but personally speaking, I find soloing over power chords kind of interesting because the "chord" isn't really major or minor, and you can come up with some interesting stuff and not be "wrong". Power chords make hard rock- maybe metal, that I'm discovering in my old age- fun and interesting. I think Jimmy Page used a lot of power chords on some classic Zep tunes. Black Sabbath's Iron Man is full of power chords (had to learn the tune from my son's Guitar Hero to teach him, lol). I'm not a big metal fan, but now that I've kind of (re) discovered it, it's fun to listen to...CRANKED UP! But metal doesn't beat classic rock! ;) fwiw, break out the theory books; nearly 40 yrs of playing and resisting theory, I now know what I've been missing.