The term "all-terrain vehicle" is used in a general sense to describe any of a number of small open motorised 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 ANSI definition, it is intended for use by a single operator. The 4-wheeled versions are most commonly called "quads," "four-wheelers" or "ATVs" in the United States and Canada, and "quad bikes" or "quad cycles" in other English-speaking countries. Models with 3 wheels are typically known as ATCs (though this is a Honda trademark[1]) and "three-wheelers," and less commonly "all-terrain cycles" and "trikes." 6- and 8-wheel models exist for specialized applications. The rider sits on these models just like on a motorcycle, but the extra wheels make them more stable at slow speeds. ATV Accessories can also be considered Off Highway Vehicles (OHV) or Off Road Vehicles (ORV), along with motorcycles, Jeeps and other off-road capable machines.
Engine sizes of ATVs currently for sale in the United States (as of 2004) range from 50cc to 800cc. They range in price from about $2000 to nearly $8000.
http://en.wikipedia.org/wiki/All-terrain_vehicle

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