What are the harmonics of a string?
Playing a string harmonic is a string instrument technique that uses the nodes of natural harmonics of a musical string to isolate overtones. Playing string harmonics produces high pitched tones, often compared in timbre to a whistle or flute.
How do you notate artificial harmonics?
The advantage of artificial harmonics is that the players can tune them to the context, whereas natural harmonics are locked in. There are two ways to notate the artificial harmonics: write the sounding pitch and put a circle above it, or write the fingered notes.