A motorcycle (also called a motorbike, bike, or cycle) is a single-track, engine-powered, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested, cruising, sport and racing, or off-road conditions. Motorcycles are one of the most affordable forms of motorized transport in many parts of the world and, for most of the world's population; they are also the most common type of motor vehicle. A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold.