This document discusses 7th chords in guitar theory. It explains that 7th chords are commonly used in jazz and country music and help define the sound of a chord. A 7th chord can be major, minor, augmented, or diminished. The 7th automatically assumes it is a flatted 7th unless specified as a major 7th. Formulas are provided for minor 7th, major 7th, and dominant 7th chords. Charts then show the fretboard positions for all 7th chords.