In horology, a tourbillon is an addition to the mechanics of a watch escapement to increase accuracy. It was developed around 1795 and patented by the Swiss-French watchmaker Abraham-Louis Breguet on June 26, 1801. In a tourbillon the escapement and balance wheel are mounted in a rotating cage, with the goal of eliminating errors of poise in the balance giving a uniform weight.
Tourbillons are still included in some modern wristwatches, the mechanism is usually exposed on the watch's face to showcase it.