Twelve-string guitar

A twelve-string guitar is a guitar with 12 strings on one neck of the guitar.

The first and second strings (high "E" and "B") are doubled, and fretted together with a single finger or a "barre".

The "third" (G) string is either doubled by a second identical string, (unison), or tuned one octave above (high "G").

The fourth, fifth, and sixth strings are doubled, but the "doubled" strings are tuned an octave above the fundamental D, A, and E strings.