Automobiles are motorized vehicles that use four wheels to move people and things over a distance. They are often driven by internal combustion engines and can carry one or more passengers. They can also be powered by electricity or hybrid-electric engines. They are a very important part of many modern societies because they make it possible to travel great distances quickly and easily without the need for long trips on foot or by horse-drawn carriage. However, automobiles can be a significant source of pollution when they are used in large numbers or for long periods of time.

The automobile revolutionized twentieth-century America by allowing people to live and work in distant locations without requiring that they walk or ride horses to get there. The industry created jobs and fueled economic growth. It also influenced the development of other industries such as steel and petroleum.

Inventors have developed a wide variety of automobile designs to meet people’s specific needs. Some are designed for off-road driving and have rugged systems with high resistance to severe overloads, while others are adapted for highway speeds and require passenger comfort options and optimized handling and stability. An attractive, functional design is also a necessity.

The modern automobile is usually powered by a gasoline internal combustion engine, but it can also be powered by a diesel or electric engine. Earlier cars included steam, electric, and water-powered models, with the gasoline internal combustion engine becoming dominant in the 1910s. A key factor in the rise of the automobile was the invention of the moving assembly line by Henry Ford at his Highland Park, Michigan, plant in 1908, which enabled a mass production of low-cost cars with affordable operating costs.

Historically, automobiles have been fuelled by petroleum (oil). As the world’s supply of petroleum began to deplete and prices rose in the 1970s, interest in alternative-fuel automobiles grew. In addition, safety and environmental concerns have encouraged many automakers to produce smaller and more fuel-efficient cars.

An automobile’s general design should be economical to manufacture and simple enough to keep maintenance costs low. It should have unobstructed all-round visibility and a good appearance. Aesthetic considerations are sometimes secondary to functional design, but an attractive shape and color are popular with consumers.

Besides standard sedans and wagons, there are coupés and SUVs. A coupe is a two-door automobile that has a sloped roofline, while an SUV has the towing capacity of a pickup truck combined with the passenger space of a sedan, hatchback, station wagon, or van. There are also hybrid-electric cars, which combine an internal combustion engine with an electric motor for power. Many of these are marketed as sports cars. They are fast and maneuverable, but they can slow down when accelerating to allow the engine to recharge.