A motor scooter is a vehicle that operates on two wheels. Its quintessential characteristics are its step-through frame, which allows its rider to straddle the seat in the manner of a bicycle, and a flat floorboard for the feet.
An ATV, or all-terrain vehicle, is a motorized off-highway vehicle with handlebars and a seat like a motorcycle, but with four tires that are optimized for control and safety when navigating unpaved roads.
A spare part, service part, or spare, is an item of inventory that is used for the repair or replacement of failed parts. Spare parts are an important feature of logistics management and supply chain management.