Automobiles are motorized vehicles that move under their own power, rather than being pulled like a bullock cart or horse carriage. Thousands of components make up the modern automobile. Unlike the human body, which is arranged into semi-independent systems, the modern car is a complex system of interrelated parts. Some of the most important are the engine, transmission system, control, and auxiliaries.
The design of an automobile depends to a large degree on its intended use. For example, a truck designed for off-road use must have durable and simple systems that can resist severe overloads and extreme operating conditions. On the other hand, an automobile built for highway driving needs improved passenger comfort options and optimized high-speed handling and stability.
During the first decades of the twentieth century, automobiles rapidly transformed American society. They allowed people to work and play in different locations, travel across country lines, and have a new freedom of movement. With this freedom came many new services, including restaurants, hotels, motels, and recreational facilities. The automobile also brought problems such as air pollution, noise, and loss of undeveloped land.
Invented in 1885 by German engineer Karl Benz, the automobile is considered one of the most significant inventions of the modern era. The automobile has become the backbone of a consumer goods-oriented economy, and it provides a major source of jobs in the United States. It is the largest user of petroleum, the lifeblood of the steel industry, and the chief customer of many other industrial products.