The term "All-Terrain Vehicle" or ATV in North America (quad-bike or quad elsewhere) is used in a general sense to describe any of a number of small open motorized buggies and tricycles designed for off-road use. However, the American National Standards Institute (ANSI) defines an ATV as a vehicle that travels on low pressure tires, with a seat that is straddled by the operator, and with handlebars for steering control. By the current ANSI definition it is intended for use by a single operator, although a change to include 2-seaters (in tandem) is under consideration.
The rider sits on and operates these vehicles like a motorcycle, but the extra wheels give more stability at slow speeds. Although typically equipped with three or four wheels, six-wheel models exist for specialized applications. Engine sizes of ATVs currently for sale in the United States (as of 2008 products) range from 49 cc to 950 cc.
