A motorcycle is a two-wheeled motor vehicle with a seat for the rider and a frame to support the engine and other components. The engine generates power by using reciprocating motion to turn the crankshaft, and this is transferred through a transmission system to the back wheel, propelling the motorcycle forward. The driver steers by shifting their center of gravity to change the direction of travel, leaning the bike to one side or another.
Many riders choose specific motorcycles to suit their tastes and purposes. These different styles can be grouped into categories, such as standard, cruiser, sport, luxury touring, dual-sport and dirt bike. Some riders are drawn to particular types of motorcycles, such as the cafe racer or bobber, while others may prefer a more practical and comfortable vehicle like the touring motorcycle.
Some countries require that motorcycles be road-legal, with features that make them safe for highway use. These usually include a larger fuel tank, a headlight that is legally required to be on at all times and a rearview mirror. Many people also install a trunk, which can be mounted above and behind the seat, to provide storage space for luggage.
Many motorcycles are used as a means of transportation, especially in poorer nations. Modern engines are often highly efficient, with a good power-to-weight ratio, making them economical for long distance travel. In general, motorcycles are easier to maneuver than cars in traffic, and can be stopped more quickly by utilizing the front brake only.