Banjo F6 chord (Open D)F sixth on the 5-string banjo: 3 3 3 0, and 6 more shapes

Frets, string 4 to string 1: 3 3 3 0 (open position)

1. String 4 (D): 3rd fret, index finger (barre), F
2. String 3 (F♯): 3rd fret, index finger (barre), A
3. String 2 (A): 3rd fret, index finger (barre), C
4. String 1 (D): open, D
5. String 5, the short f♯: open, F♯, not in the chord

Sounds: F A C D  ·  F6 is F, A, C, D (1 · 3 · 5 · 6)

The 5th string: the short f♯ rubs against the F in this shape, a semitone away: some players let it ring, some skip it.

Open D tuning: f♯DF♯AD, the short 5th string first, then strings 4 to 1.