Tapping the guitar is a soloing/riffing technique used mostly by metal virtuoso guitarists but is as well used somewhat in other genres. The Tapping technique using your fingers on the right hand (the picking hand) to do a “hammer on” on the string usually on the higher frets of the guitar to achieve faster licks. This is exactly the same as doing a “hammer on” with the left hand but instead of using the left you “Tap” with your right.
In this video we have two very simple examples to start you off on your tapping journey. They are played relatively slow so try speeding them up. You can also move the exercise as a whole between the strings or up and down the fretboard.
Check out this example of Stanley Jordan master tapper. He uses 4 fingers on each hand to Tap complicated melodies. Now if you’re tapping with both hands using 4 fingers on each you are basically playing the guitar like you would a piano.