The hurdy-gurdy is a stringed instrument that produces sound by a hand-cranked, rosined wheel rubbing against strings. The wheel functions much like a violin bow, and the notes are played by pressing keys that move 'tangents' against the strings to change their pitch. It usually features 'drone' strings that provide a continuous pitch, similar to bagpipes. One of its most distinctive features is the 'trompette' or buzzing bridge; when the player cranks the wheel with specific rhythmic pulses, the bridge vibrates against the soundboard to create a rhythmic buzzing sound. Originally used in medieval churches and later by Renaissance troubadours, it became a popular folk instrument across Europe. Its complex internal mechanics make it one of the most difficult instruments to maintain and tune, as the wooden wheel must be perfectly round and the cotton wrapping on the strings must be applied with extreme precision.