A wheel and axle is a simple machine that consists of a circular wheel attached to a central rod called an axle. When the wheel turns, the axle rotates with it, allowing for easier movement of heavy objects. This design reduces friction and makes it simpler to lift or transport loads. Common examples of the wheel and axle include bicycles, cars, and carts. In these applications, the wheel provides a larger surface area for rolling, while the axle serves as the pivot point. Together, they enhance efficiency in movement and are fundamental in various transportation methods.