Playing by guitar tapping (or bass) means tapping the fingers upon the fretboard strings to create notes. You don't have to strum or pick. Generally this is the called two-handed tapping, which means using this tapping technique with both the right and left hand.

Tapping like this, you can play bass and rhythm guitar at the same time. Guitar and bass tapping can be used for songs from the baroque period, and two-part songs as given in piano scores, and as exemplified in Bach's Two-Part Inventions.

You can use two handed tapping for playing multinote music and music with counter-harmonies on a guitar or one of the several specialty instruments created for two-handed tapping, and created for the tapping method.

Tapping can be used for playing right-handed melodies and left-handed harmony something like piano playing

You can use both hands on high-pitched strings for playing melodies and improvising solos with extremely rapid flurries of notes, or alternately upon the bass strings for playing funky, funky bass lines. In several ways this feels very much like two-handed 'drumming' on the strings.

The two hand tapping method is quite simple. Plug in an electric guitar, electric bass, or a specialty tapping instrument like the Chapman Stick. Turn up your amplifier. Tap a string to a fret. Presto! You've played a note. Naturally, learning this powerful method of playing music will require you to practice. All the same, if you're using a sensible learning method, and a sensible tuning that is familiar to you from your guitar and bass experience, progress can be pleasingly rapid.

Two handed tapping is sometimes called 'touchstyle,' or 'touch style,' because playing a single note can feel more like gently stroking than actually hitting the string. This is done on an amplified instrument to make the notes audible. Because it can be done with both hands, both hands can be used simultaneously, like a piano player in a way.

Making a note on an amplified instrument isn't at all difficult. Though become proficient in the two-handed tapping method could fill a lifetime, in actual fact, many wonderful forms of musical expression can be produced fairly quickly, and the practice is almost universally reported to be hugely fun by people who try the technique.