A thermosyphon is a passive heat exchange system that circulates fluid without the need for a pump. It relies on the natural convection of liquids or gases, where warmer, less dense fluid rises while cooler, denser fluid sinks. This process creates a continuous flow, allowing for efficient heat transfer. Commonly used in applications like solar water heaters and radiators, a thermosyphon can effectively move heat from one area to another. The system typically consists of a heat source, a heat transfer medium, and a heat sink, making it a simple yet effective solution for thermal management in various settings.