A headstock or peghead is part of a guitar or similar stringed instruments such as a lute, mandolin, banjo, ukulele and others of the lute lineage. The main function of a headstock is to house the tuning pegs or other mechanism that holds the strings at the "head" of the instrument; it corresponds to a pegbox in the violin family. At the "tail" of the instrument the strings are usually held by a tailpiece or bridge. Machine heads on the headstock are commonly used to tune the instrument by adjusting the tension of strings and, consequently, the pitch of sound they produce.

The guitar is a stringed musical instrument that is usually fretted and typically has six or twelve strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected strings against frets with the fingers of the opposite hand. A guitar pick may also be used to strike the strings. The sound of the guitar is projected either acoustically, by means of a resonant hollow chamber on the guitar, or amplified by an electronic pickup and an amplifier.