Automobiles are vehicles that can be propelled by an engine and used for the transport of passengers or cargo. They are commonly fueled by petroleum, but many manufacturers also produce automobiles that run on alternative fuels such as electricity and hydrogen. The technology of the automobile has had a profound effect on the economy, social structure and culture of modern society. An automobile is a complicated technical system composed of several subsystems, including the body, chassis, engine, drivetrain, control systems and safety features. New technologies have constantly been integrated into automobiles, resulting in improved performance and reduced emissions.

The invention of the automobile has transformed societies, allowing people to live far more independent lives than ever before. It has provided the freedom of rapid, long-distance travel and made possible the flexible distribution of goods that is crucial to the global economy. While these benefits are considerable, they have also led to traffic congestion and environmental damage, especially in urban areas.

While the concept of automobiles dates back to the late 1700s, it was American automaker Henry Ford who revolutionized car production and introduced pricing that allowed most middle-class families to afford a car. Ford also pioneered assembly line techniques that enabled the manufacturing of many identical automobiles, dramatically lowering their cost.

A modern automobile is usually driven by a water-cooled piston-type internal combustion engine that may be powered by gasoline, diesel or other fuels. The engine drives the wheels through a transmission, which may transmit power to the front or rear axles, or to all four. The choice of which wheels to drive depends on factors such as the size and weight of the vehicle, its suspension characteristics, and its aerodynamic centre of pressure and balance of weight.

An automobile’s braking system uses friction to reduce speed or hold the vehicle stationary. Each wheel has a brake pedal, which pushes a disc or drum against the surface of the road. The rubbing action between the brake surface and the road generates heat, which melts and absorbs a portion of the kinetic energy of the moving vehicle.

The body of an automobile includes the frame, suspension, braking system, and wheels and tires. It also contains the cabin, where the driver and passengers are protected from the elements. The body is often designed to meet a number of standards, including safety and aesthetics. The modern automobile’s engine is typically a multi-cylinder unit, with from four to eight cylinders. Each cylinder works in a cycle, beginning with the intake stroke and ending with the compression stroke, to turn the crankshaft of the motor. An automobile’s electrical system requires a battery, which provides the force needed to start the engine. The battery then feeds the engine by supplying electric current through the engine’s spark plugs. The motor’s alternator then recharges the battery to provide electricity for the starter and other automotive systems. A vehicle’s engine also needs oil to lubricate its parts and reduce wear.