Guitar skills: 'Add’ chords come in the form of either ‘add9’ or ‘add11’. The name tells you to add either a 9th or 11th interval to a basic major or minor chord. So, Cadd9 is a C chord ...

This is the chord that most players associate with Summers’ style. As the name suggests, an Add9 power chord is a power chord with an additional 9th note added at the top, creating an Add9.