Guitarist Stanley Jordan Sitting In w/ The Roots @ Jimmy Fallon (2015)

"Normally, a guitarist uses two hands to play each note. One hand presses down a guitar string behind a chosen fret to prepare the note, and the other hand either plucks or strums the string to play that note. Stanley Jordan's touch technique is an advanced form of two-handed tapping. The guitarist produces a note using only one finger by quickly tapping (or hammering) his finger down behind the appropriate fret. The impact causes the string to vibrate enough to sound the note, and the volume can be controlled by varying the force of impact. Jordan taps with both hands, and more legato than is normally associated with guitar tapping. His technique allows the guitarist to play melody and chords simultaneously.

He plays guitar in all-fourths tuning, from bass to treble EADGCF (all in perfect fourths as on the bass guitar) rather than the standard EADGBE. He has stated that all-fourths tuning 'simplifies the fingerboard, making it logical'.

Jordan's main guitar was built by Vigier Guitars in 1988: it is an Arpege model on which Vigier made a flat fingerboard, allowing it to have a very low action (0.5/0.7mm). The low action facilitates the tapping technique."

https://en.wikipedia.org/wiki/Stanley_Jordan