Steam trains are locomotives powered by steam engines, which use boiling water to create steam that drives pistons. These trains were first developed in the early 19th century and played a crucial role in the expansion of rail transport, allowing for faster and more efficient movement of goods and people. The steam engine operates by burning fuel, typically coal, to heat water in a boiler. The resulting steam is then channeled into cylinders, where it pushes pistons to turn the wheels. Famous examples of steam trains include the Locomotion No. 1 and the Flying Scotsman, which showcase the engineering marvels of their time.