All-terrain vehicle
An all-terrain vehicle is usually a four wheel vehicle designed for off-road use, also called a quad. Models with 3 wheels are called ATCs. 6 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.Honda made the first ATC models for use by farmers. The ability to go anywhere on terrain that most other vehicles could not cross soon made them popular with hunters, and those just looking for a good trail ride. Soon other manufacturers introduced their own models.
Safety issues with 3 wheels caused all manufaturers to switch to 4-wheeled models in the late 80's, and 3-wheel models are no longer made. The lighter weight of the 3-wheel models make them popular with some expert riders. The safety issues were in cornering, all models have a solid rear axel, to corner the rider needed to reduce speed more than expected, and lean out. This is contrary to instincts and all other vehicles, so many riders were injured.
Models today are roughly divided into the sport and utility markets. Sport models are generally small, light, 2 wheel drive, and go fast. Utility models are generally bigger, 4 wheel drive, max out at about 45mph, and have the ability to haul small loads. Due to the weight, both have advantages on different types of terrain.
6 wheel models have a small dump bed, with an extra set of wheels in the back to increase the payload capacity. They can be either 4 wheel drive (back wheels driving only), or 6 wheel drive.
There also exist 6 and 8 wheel models where the rider sits inside. These vehicles float and are designed to go though swamps as well as dry land.