Chords are three or more notes played simultaneously.
Use of the chord root note,
Moveable chords.
The circled note indicates the root note of the chord.
The most important chords in Rock music are the E and A chords. These two chords form the foundation of classic rock bar chords. They are moveable chords and by being moveable this allows rock musicians to create that familiar guitar sound we know and love.
Bar chord using index finger - Bar chord using thumb.