External combustion engines are machines that generate power by burning fuel outside the engine itself. In these engines, the heat produced from combustion is used to create steam or hot gases, which then drive a piston or turbine to produce mechanical work. Common fuels include coal, wood, and oil. One of the most well-known examples of external combustion engines is the steam engine. These engines played a crucial role in the Industrial Revolution, powering trains and factories. Unlike internal combustion engines, where fuel burns inside the engine, external combustion engines offer advantages in efficiency and fuel flexibility.