A mainspring is a coiled spring that stores energy in mechanical devices, particularly in watches and clocks. When wound, it tightens and stores potential energy, which is gradually released to power the movement of gears and hands, keeping time accurately. In addition to timepieces, mainsprings are also used in various mechanical devices, such as musical boxes and wind-up toys. The design and material of a mainspring can affect its performance, durability, and the overall efficiency of the device it powers.