Automatic watches are powered by the movement of the wearer’s wrist. Inside the watch is a rotor that moves as you move your arm, winding the mainspring and storing energy to keep the watch running. This means that automatic watches don't require batteries, however, some models may require manual winding if not worn for an extended period.

If an automatic watch is left unworn for an extended period, it will stop. You can either wind it manually to get it started again or wear it to allow it to wind itself with movement.

The lifespan of an automatic watch can vary depending on the quality of the movement and how well it is maintained. With proper care, a high-quality automatic watch can last for many decades, even generations.