A steam wagon (or steam lorry, steam waggon or steamtruck) is a steam-powered truck for carrying freight. It was the earliest form of lorry (truck) and came in two basic forms: overtype and undertype, the distinction being the position of the engine relative to the boiler. Manufacturers tended to concentrate on one form or the other. Although the majority of steam wagons have been scrapped, a significant number have been preserved in working order and may be seen in operation at steam fairs, particularly in the UK.