Automobiles are wheeled vehicles that have seats for one or more people and an engine to make them move. They use gasoline as their fuel, although some run on alternative energy sources like electricity. They have a steering wheel to help them turn, brakes to slow or stop them, and a gearbox to change speed or direction. Almost all have an instrument panel to show the vehicle’s speed, fuel level and other information.

The branches of engineering that study automobiles are known as automotive engineering. These engineers work on the design, manufacture and technology of these cars. They test drive vehicles to see how they perform, and they design improvements to improve safety and performance. They also design new car engines, transmissions, body systems, electrical systems and other components.

Invented in the late nineteenth century, automobiles revolutionized transportation. They are so widespread that modern life seems almost inconceivable without access to a car, which is used to travel more than three trillion miles (five trillion kilometres) annually. They have shaped urban and rural designs, as well as government services such as police, fire, highways and airports. They have also helped open up new leisure activities, such as shopping, dining and vacation trips.

Although a number of inventors and engineers worked on the automobile, history usually credits Karl Benz from Germany with inventing it around 1885. He was not the first to create a motor vehicle, but his design enabled automobiles to be manufactured in large numbers, which made them more affordable. By the early 1910s, Henry Ford had innovated manufacturing techniques to lower production costs even more. He sold his Model T for less than the average American’s annual wage, so many middle-class families could afford a car.

In the United States, where more than half of all passenger cars are made, demand for automobiles was fueled by a large population and a relatively equal distribution of income between rich and poor households. Cheap raw materials and a long tradition of industrial manufacturing also encouraged auto companies to build in large quantities. The resulting economies of scale allowed companies such as General Motors, Ford and Chrysler to become the dominant players by 1920.

With the end of World War II, a period of economic prosperity followed, and automobile production rose rapidly. This boom triggered the formation of new industries such as automobile parts suppliers, manufacturers of car accessories and specialized equipment like fork-lifts, and car dealerships. In addition, consumers demanded more fuel-efficient vehicles, which led to new technical innovations. This period of growth continued until the 1973 oil crisis, after which demand for automobiles began to decline. It has since slowly rebounded. Today, automobiles continue to play a major role in human society, and the field of automotive engineering continues to evolve with rapid technological advances.