Watch the Melody: More Power To You online guitar lesson by Matthieu Brandt from Songwriting on Guitar
Ever since the 60's, power chords in rock and pop have been widely used. Power chord are two note chords (a root and a perfect fifth above the root) that create a lot of options. Because these chords don't contain a third, they're neither major nor minor. The tonality can be chosen by the composer and can swing both ways. Often the major or minor tonality is formed by the set of chosen chords for a composition. In Hard Rock, Metal and Grunge the tonality if almost always minor, but a major melody is also an option.