What is the white stern light for sailboats?

The white stern light on sailboats is a navigation light that is required by maritime regulations. It is positioned at the stern (rear) of the vessel and serves to indicate the boat's presence and direction to other vessels at night or in low visibility conditions. The light must be visible from a certain distance and helps prevent collisions by allowing other boats to determine the sailboat's orientation and movement. In combination with other navigation lights, it plays a crucial role in maintaining safety on the water.