An automobile, or car, is a self-propelled vehicle for travel on land. Powered by a gas or electric motor, it has four wheels and carries two to six passengers plus a limited amount of cargo. It is distinct from a truck, which is used primarily for the transportation of goods and is constructed with heavier parts, and a bus, which carries many passengers, and sometimes small amounts of cargo.
The scientific and technical building blocks for the automobile date back several hundred years, when Dutch scientist Christiaan Huygens created a type of internal combustion engine sparked by gunpowder. However, it was Karl Benz who introduced the modern automobile in 1885 with his four-wheeled, gasoline-powered motorcar. The automobile opened up a new world of opportunities, giving people more freedom to move, work, and socialize. It also prompted the development of better roads, and industries and services to support and use them.
By the end of the 1920s, the number of cars in the United States had reached 26 million. With the end of World War II, the number climbed to 60 million. It was a time of suburbanization, drive-in movies and restaurants, interstate highways and other forms of mass transportation, and a more mobile workforce that enabled families to move together for work and leisure. It also spawned the development of new laws, including those on driving safety and traffic regulations, and brought the need for improved and safer vehicles and fuel.
Automobiles are the primary mode of transportation for the majority of people in most industrialized countries. They account for about 70 percent of all passenger trips worldwide. The automobile is also a major source of air pollution, and its emissions of greenhouse gases contribute to climate change. The use of gasoline, which is a fossil fuel, also causes pollution and can lead to the depletion of natural resources.
A variety of technologies are being developed to make automobiles more environmentally friendly and safer. For example, some manufacturers offer hybrid vehicles that run on a combination of electric and gasoline power. The electric motor runs the vehicle during braking and slowing, while the gasoline engine takes over when cruising.
Another area of research focuses on the development of an autonomous or semiautonomous automobile, in which the computer controls or aids the human driver. Such systems may monitor the environment and road conditions, and adjust vehicle speed or direction, depending on traffic signals, other vehicles, or pedestrians. Some systems also can detect and avoid obstacles in the path of the vehicle. The first practical automated vehicles may be ready for commercial use by the early 21st century. In the meantime, many automakers have begun to include automatic safety equipment like tire pressure monitoring and stability control on all models. These technologies are becoming more common as they become cheaper to develop and introduce. Moreover, they are being made mandatory by government agencies.