A motorcycle or motorbike is a single-track, two-wheeled motor vehicle powered by an engine. Styles of motorcycles vary depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions. In many parts of the world, motorcycles are among the least expensive and most widespread forms of motorised transport.---------------Touring motorcycles: Touring bikes are designed for rider and passenger comfort, luggage carrying capacity, and reliability. Cruisers, sport bikes and some dual-sports can also be used as touring bikes with the addition of after-market luggage and sometimes seats. Common throughout the touring market are usually large-displacement fairings and windshields (for weather and wind protection), large-capacity fuel tanks (for long-range travel), engines optimised for progressive torque rather than highest possible power, and a more relaxed, basically upright seating position.