CAGED System  

The #CAGEDsystem is an acronym for the chords C, A, G, E, and D. This acronym is often used as a shorthand way of describing the use of barre chords that can be played anywhere on the fret board as described above. It is often used by guitar instructors as a way to remind students of the open chords that can be used as #barrechords across the #fretboard. 

By replacing the nut with a full barre, the chord shapes for C, A, G, E and D may be used anywhere on the fret board to play any major chord in any key. This system is also used as a way to remember scale shapes, though the usefulness of this teaching method is debated due to potential technical problems.[3]  weki