Automobiles are powered by an internal combustion engine that burns a fuel such as gasoline, diesel fuel or another petroleum product. They are designed for passenger transportation and may carry two to six passengers. A car (or auto) is distinguished from a truck, which is designed for the transport of cargo, and a bus, which is designed to carry large numbers of passengers.

The automobile is one of the world’s most widely used vehicles, and its development has profoundly shaped modern life. By the end of the 20th century, it was impossible for most people in developed countries to get around without access to a car. This remarkable achievement stemmed largely from the innovation of U.S. carmaker Henry Ford, who streamlined production methods in his factories. He was the first to employ assembly lines, which made it possible to produce cars at a rate that put them within the financial reach of middle-class families.

The automotive industry has many sub-sectors that specialize in the manufacture of specific parts or the design and construction of complete vehicles. Some of these include axles, brakes, transmissions and engines. The design and development of new technologies in the field of automobiles has also been influenced by environmental concerns, as well as by consumer demand for increased safety features.

While the automobile was developed in Europe in the late 1800s, American carmakers came to dominate the industry in the first half of the twentieth century. The country’s vast land area and unequal distribution of income encouraged greater demand for automobiles than existed in Europe. Cheap raw materials and a strong tradition of industrial manufacturing helped bring costs down. In addition, the lack of tariff barriers facilitated sales over a wide geographic area, further fueling demand for the automobile.

Despite these advantages, automobiles had to overcome the formidable obstacle of cost. Early automobiles were expensive and difficult to operate. The German engineer Karl Benz invented the first automobile in 1885, and American businessman Henry Ford revolutionized manufacturing techniques to produce affordable models such as his Model T, making the automobile available for the masses.

In addition to private cars, there are special automobiles for use in a variety of jobs, such as police cars and fire engines. Other automobiles that are in use are crane cars at construction sites, and vehicles used at ports for loading and unloading cargo.

Work continues on the development of an automobile in which a computerized system greatly aids or even replaces the human driver. This technology, called semiautonomous driving, is still a long way from becoming practical for everyday use. In the meantime, manufacturers have begun including a number of automatic safety systems that sense conditions that could lead to vehicle instability or collision and take appropriate action. These features are known as crash avoidance systems.