Fingering
Fingering on string instruments will show which position to play in (i.e. how far down the fingerboard the hand is held).  The fingers are numbered from 1 to 4 because the thumb is behind the neck of the instrument.  The number 0 means: play an open string (not using the finger).  It is only the left hand which fingers the notes because the right hand is either plucking or bowing.  Bowed instruments like the violin have no markings on the fingerboard, so the player has to get used to the exact place to put the fingers, otherwise it will not be in tune.  Plucked instruments such as guitars and banjos have frets (little bumps on the fingerboard) which show where to put the fingers.