A tractor is a vehicle specifically designed to provide a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction.
Most commonly, the term is used to describe the distinctive farm vehicle: agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
The first powered farm implements in the early 1800s were portable engines – steam engines on wheels that could be used to drive mechanical farm machinery by way of a flexible belt.
Around 1850, the first traction engines were developed from these, and were widely adopted for agricultural use. Where soil conditions permitted, such as the US, steam tractors were used to direct-haul ploughs, but in the UK, ploughing engines were used for cable-hauled ploughing instead. Steam-powered agricultural engines remained in use well into the 20th century, until reliable internal combustion engines had been developed.