The bicycle is a two-wheeled vehicle used for transportation, exercise and recreation. Over a billion people use bicycles worldwide. They are an efficient means of transport, with the ability to carry a load. They are also environmentally friendly, producing less pollution than cars. Cycling is a low impact activity, and provides a good muscle workout. It is easy to get into, and can be done by most people of all ages.

In cities around the world, bicycles are the dominant mode of transport. They outsell automobiles three to one. Cycling reduces traffic congestion, and can be a fun way to spend time outdoors. It is also a great form of exercise, and it can burn anywhere from 400 to 1000 calories per hour. Cycling helps to strengthen the legs, back, abdominal and core muscles. It can also help to improve balance and coordination.

Some common bicycle-related injuries include compression of the nerves in the wrists from gripping the handlebars, pain in the neck, shoulders and back from overuse; hip pain caused by sliding of the soft tissue of the hip over the underlying bone from repetitive motions; soreness or bruising in the area of the genitals from friction against the bicycle saddle; and head injury from contact with motor vehicles and other obstacles.

Bicycle-related deaths and injuries are a major concern. Most of these involve collisions with motor vehicles, but other causes include falls and crashes involving other bikes, pedestrians and stationary objects such as trees and signs. A helmet is recommended for all cyclists. It is essential to maintain a safe speed and distance from other road users, and to keep an eye out for potholes, gravel and ruts.

A bicycle can be purchased from a specialty bike shop or from some department stores. Basic models may come with platform pedals, but most higher-end models are sold without pedals, assuming that the buyer will already have his or her preferred pedal system. Many bicycles also have rack mounts to allow attachment of luggage or baskets.

In some countries, laws require bicycles to have a rear-view mirror and reflectors, and to be fitted with front and rear lights for safety. Some states also require that bicycles be licensed and insured.

Cycling is a great way to get exercise while having fun and saving money. It can also be a great alternative to driving a car, especially in urban areas where parking is difficult and expensive. It can be a convenient way to get to work, school and other places. It is also an excellent choice for commuting long distances, as it can be faster than traveling by bus or train. It can also be a good way to travel with children. A family that commutes by bicycle can reduce their carbon footprint by 67%, according to a European study. Commuting by bike also can be a cheap way to travel to sports events and other leisure activities. It can even be a way to get groceries in some cities.