A tractor is a large truck or semi-trailer that is towed by tools between the front and the carriage. That is, the front of the vehicle can be separated from the original carriage and tow other carriages, and the carriage can also be separated from the original front and towed by other fronts. The front of the vehicle with driving ability is called a tractor, and the vehicle without traction driving ability at the back is called a trailer. The trailer is towed by the tractor. There are two ways to connect the tractor and the trailer: the first is that the front half of the trailer is placed on the traction saddle on the rear section of the tractor, and the bridge behind the tractor bears part of the weight of the trailer, which is a semi-trailer; the second is that the front end of the trailer is connected to the rear end of the tractor, and the tractor only provides forward pulling force and tows the trailer, but does not bear the downward weight of the trailer, which is a full trailer.
It is often used for the transportation of large quantities of goods within or between workshops, such as transportation from automobile manufacturing warehouses to assembly lines and luggage transportation at airports.