A bicycle is a human powered land vehicle consisting of a seat, two wheels, and two pedals. It also has a frame to give it strength, and a metal chain connected to cogs on the pedals and rear wheel that are driven by the rider’s feet. It is used for transportation, recreation and exercise, and many other purposes. Bicycles are widely used and are the most common form of transportation in the world. Bicyclists must abide by traffic rules and regulations when using them on public roads. They must wear helmets, reflective clothing and have a white front light and red rear reflector on their bikes when using them at night or in low visibility conditions.

The bicycle is the most efficient means yet devised for converting human energy into motion. Historians disagree about the exact date of its invention, and it is most likely that no single person qualifies as the inventor of the bicycle. The first bicycles had wooden frames with a front-wheel drive and were powered by cranks attached to the pedals. This design was difficult to ride and prone to accidents, but improvements in materials and the development of gears enabled the first modern bicycles to be built in the later 1800s.

Some early bicycles were designed with the wheels very close together, requiring the rider to shift his or her weight between the two wheels in order to change direction. The introduction of pneumatic tires and the chain drive made this a less difficult task. The invention of the safety bicycle in the 1880s changed the face of cycling, making it a popular sport and a practical mode of transport.

Today’s bicycles are manufactured from a wide range of materials, including steel, aluminum, titanium and carbon fiber. They are lighter and stronger than ever before, and there is a large variety of styles and sizes available to meet the needs of any rider. Some models are designed to be used for racing and competition, while others are geared toward everyday use.

There are many reasons for riding a bicycle, including the health benefits of regular exercise and the convenience of transportation in cities. Bicycles can maneuver through traffic more quickly than motor vehicles, and they are a popular form of transportation for young people. Many schools offer bike programs to encourage their students to commute to school by bicycle, and some communities have even created dedicated bike lanes on major streets.

In the United States, there are more than a billion bicycles in operation, and they are the most popular form of transportation for people aged 15 and over. In addition to recreational riding, bicycles are used for fitness, military and police applications, courier services and bicycle racing. Bicycles can also be used for work in manufacturing and other industries, although this is usually limited to the transportation of small parts between production areas. This type of cycling is known as utility cycling. Some organizations even employ bicycle-mounted emergency medical services to navigate city streets more quickly than a traditional ambulance can.