Wheels can be fastened on a [wheel axle]? and attached to a vehicle. The wheel will then roll over the ground. Compared to a vehicle without wheels, such as a sled?, the friction from "ground against vehicle" is largely eliminated and replaced with friction from "wheel axle against socket", where a lubricant or group of bearings may minimize it. Movement is thereby achieved with much less friction which means much less work is necessary.
The wheel is often viewed as the quintessential invention?, and was most likely invented in all ancient civilizations, although not always used.
In order for wheeled vehicles to work well, one must employ them on roads, or fit the vehicle with superior suspension?.
Variations on wheels produce the pulley and the windlass?.
A development of wheels to allow them to travel through rough terrain is the track found on some tractors and armored vehicles.