A wagon is a heavy four-wheeled vehicle pulled by draught animals or on occasion by humans, used for transporting goods, commodities, agricultural materials, supplies, and sometimes people. Wagons are distinguished from carts, which have two wheels, and from lighter four-wheeled vehicles primarily for carrying people, such as carriages. train wagon, is a vehicle used for the carrying of cargo or passengers on a rail transport system. Such cars, when coupled together and hauled by one or more locomotives, form a train. Alternatively, some passenger cars are self-propelled in which case they may be either single railcars or make up multiple units.