Watch the Additional Chord Vocabulary online guitar lesson by Angus Clark from Hard Rock Survival Guide: Rhythm
There's a whole bunch of chords outside of the standard major, minor, and power chord voicings we've been looking at throughout this course. These are 7th chords, suspended chords, extended chords, or altered chords. Intimidated? Don't be.
Here are a couple of useful 7th chord shapes, one with the root on the sixth string, one with the root on the 5th string.
Extensions are any note that a jazzer would refer to with a number higher than 7. Those are 9, 11, and 13 - which are the 2nd, 4th, and 6th notes of the scale. The implication here is that you still have the third of the chord involved, and if it's jazz you would pretty much always have the 7th. But this isn't jazz. Here are a couple of useful voicings that will add some color to your sound.
Altered chords are chords where one or more voices have gone completely out of whack on you and they are a half step off from where they'd be if you were just playing out of the major scale of the root you're basing the chord from. The most popular of these is the dominant 7#9 chord. Remember, hard rock is still rock, so it's still blues-based music. So don't be afraid to drop a dominant 7 chord on the nice folks.