hurdy gurdy or hurdy-gurdy (also known as a wheel fiddle) is a stringed (String instrument) musical instrument that produces sound by a crank-turned rosined wheel rubbing against the strings. The wheel functions much like a violin bow, and single notes played on the instrument sound similar to a violin. Melodies are played on a keyboard (Musical keyboard) that presses tangents (small wedges, usually made of wood) against one or more of the strings to change their pitch. Like most other acoustic string instruments, it has a soundboard (sounding board) to make the vibration of the strings audible.

Most hurdy gurdies have multiple "drone (drone (music)) strings," which provide a constant pitch accompaniment to the melody, resulting in a sound similar to that of bagpipes. For this reason, the hurdy gurdy is often used interchangeably with or along with bagpipes, particularly in French (French folk music) and contemporary Hungarian (Hungarian music) folk music. Many folk music festivals in Europe feature music groups with hurdy gurdy players, but the most famous annual festival is at Saint-Chartier, in the Indre d�partement, in central France, during the week nearest July 14 (Bastille Day).