Open D tuning
Paul Davids
In this tuning, each open string is tuned to the notes of a chord, so when the strings are played individually, they form that chord. For example, in open D tuning, the open string notes are D, A, D, F♯, A, and D, which are the three notes that make up a D major chord. Open D tuning is popular and can be used for acoustic or electric guitars. It's often used in styles like classical, folk, blues, and heavy rock.