Strum open for an instant G chord — the Rolling Stones/blues-slide tuning. Low to high: D G D G B D.
Open G tuning is, from the low (6th) string to the high (1st) string, D G D G B D.
Start in standard tuning. Lower the 6th string (E) to D, the 5th string (A) to G, and the 1st string (E) to D. Strum open and you get a G major chord — the slide/blues tuning of Keith Richards and Robert Johnson.
Popular songs in Open G tuning include Start Me Up by The Rolling Stones, Brown Sugar by The Rolling Stones, Honky Tonk Women by The Rolling Stones.
Strum open for an instant G chord — the Rolling Stones/blues-slide tuning.
More tunings: see all 19 tunings · standard tuning chart