A fret is any of the thin strips of material, usually metal wire, inserted laterally at specific positions along the neck or fretboard of a stringed instrument. Frets usually extend across the full width of the neck. On some historical instruments and non-European instruments, frets are made of pieces of string tied around the neck.

The neck is the part of certain string instruments that projects from the main body and is the base of the fingerboard, where the fingers are placed to stop the strings at different pitches. Guitars, banjos, ukuleles, lutes, the violin family, and the mandolin family are examples of instruments which have necks. Necks are also an integral part of certain woodwind instruments, such as the saxophone.