These thin metal strips are mounted on the long necks of these stringed instruments. The frets help the musician playing the instrument to know where to place their fingers on the instrument.
On historical instruments and some non-European instruments, pieces of string tied around the neck are frets.
Frets divide the neck into sections related to a musical framework. On instruments such as guitars, each fret marks one semitone in the standard western system where one octave is divided into twelve semitones.