Puffing Billy is the world's oldest surviving steam locomotive, constructed in 1813–1814 by colliery viewer William Hedley, enginewright Jonathan Forster and blacksmith Timothy Hackworth for Christopher Blackett, the owner of Wylam Colliery near Newcastle upon Tyne, in the United Kingdom. It was employed to haul coal chaldron wagons from the mine at Wylam to the docks at Lemington in Northumberland.

A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,700 times. Functionally, it is a steam engine on wheels.