A Stirling engine is a type of heat engine that converts thermal energy into mechanical work. It operates by cyclically compressing and expanding a gas, typically air or helium, within a closed system. This process creates pressure differences that drive a piston, producing motion. The engine is known for its high efficiency and ability to use various heat sources, including solar energy and waste heat. Unlike traditional engines, the Stirling engine operates quietly and has fewer moving parts, which can lead to lower maintenance costs and longer lifespans.