Open C tuning

Open C tuning is an open tuning for guitar. The open-string notes form a C major chord, which is the triad (C,E,G) having the root note C, the major third (C,E), and the perfect fifth (C,G). When the guitar is strummed without fretting any strings, a C-major chord is sounded. By barring all of the strings for one fret (from one to eleven), one finger suffices to fret the other eleven major-chords.