open tuning
A guitar tuning where the open strings form a complete chord without fretting.
In Depth
In open tunings, strumming all open strings produces a major or minor chord. Open D (D-A-D-F#-A-D), open G (D-G-D-G-B-D), and open E are the most common. Open tunings are essential for slide guitar, as the slide can produce full chords by laying flat across the strings at any fret. They also enable unique voicings and drone effects impossible in standard tuning.
Keith Richards of the Rolling Stones plays almost exclusively in open G tuning with the low E string removed, giving his guitar work its distinctive five-string sound.