ATV (All-terrain vehicle) is also known as quad, quad bike, three-wheeler, or four-wheeler. ATVs are used to traverse any terrain for hunting, mudding or any other outdoor activity. The engine sizes range from 49 to 1,000 cc (3 to 61 cubic inches). ATVs can even have up to 6 wheels and are then referred to as AATV (Amphibious ATV). Some ATVs are made for racing and sport competition. It is important to be safe while on ATVs. Proper safety gear should be warn. Helmets and a reflective vest are recommended.