Open C tuning is not as common as the other tunings but has been included because of its different sound. The sixth string is lowered two tones (two frets).The fifth and fourth strings are lowered one tone (two frets) and the second string is raised one semitone. The open string notes as shown in the following diagram will therefore be, beginning with the sixth string;
These notes form a C major chord. A C major chord consists of the notes C, E and G.