Cycling, also called bicycling or biking, is the use of bicycles for transport, recreation, or for sport. Persons engaged in cycling are cyclists or bicyclists.

Cycling is a very efficient and effective mode of transportation optimal for short to moderate distances. Bicycles provide numerous benefits compared to motor vehicles, including exercise, an alternative to the use of fossil fuels, no air or noise pollution, much reduced traffic congestion, easier parking, greater maneuverability, and access to both roads and paths.

Bicycles are often used by people seeking to improve their fitness and cardiovascular health. In this regard, cycling is especially helpful for those with arthritis of the lower limbs who are unable to pursue sports that cause impact to the knees and other joints. Since cycling can be used for the practical purpose of transportation, there can be less need for self-discipline to exercise.

The physical exercise gained from cycling is generally linked with increased health and well-being. According to the World Health Organization, physical inactivity is second only to tobacco smoking as a health risk in developed countries, and this is associated with many tens of billions of dollars of healthcare costs. The WHO`s report suggests that increasing physical activity is a public health "best buy", and that cycling is a "highly suitable activity" for this purpose. The charity Sustrans reports that investment in cycling provision can give a 20:1 return from health and other benefits. It has been estimated that, on average, approximately 20 life-years are gained from the health benefits of road bicycling for every life-year lost through injury.