It’s common to use an open tuning to play slide guitar. This allows us to tune so that when we play all the strings open it sounds as a chord. For example, let’s take the open D tuning. Once we’re tuned to open D, a D chord will sound when we play the strings open, no fretted notes needed.
The main reason that we do this is that of the shape of the slide. It’s easier to hit adjacent notes that are in tune. That way we don’t have to slide all over the place in order to hit notes for a lead part and it allows us to form chords. It’d almost be impossible to play full chords without tuning to an open tuning.
Open D tuning, also called ‘Brady Clark Tuning’ is an open tuning for the acoustic or electric guitar.
The open string notes in this tuning are D, A, D, F#, A, D (from low E to high E). It uses the three notes that form the triad of a D major chord:
D, the root note A, the perfect fifth and F#, the major third When the guitar is strummed without fretting any of the strings a D major chord is sounded. This means that any major chord can be easily created using one finger, fretting all the strings at once (also known as barring); for example, fretting all the strings at the second fret will produce an E major, at the third fret an F major, and so on up the neck.