A nut, on a stringed musical instrument, is a small piece of hard material that supports the strings at the end closest to the headstock or scroll. The nut marks one end of the vibrating length of each open string, sets the spacing of the strings across the neck, and usually holds the strings at the proper height from the fingerboard. Along with the bridge, the nut defines the scale lengths (vibrating length) of the open strings.
The nut may be made of ebony, ivory, cow bone, brass, Corian, Tusq or plastic, and is usually notched or grooved for the strings. The grooves are designed to lead the string from the fingerboard to the headstock or pegbox in a smooth curve, to prevent damage to the strings or their windings. Bowed string instruments in particular benefit from an application of soft pencil graphite in the notches of the nut, to preserve the delicate flat windings of their strings.
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