Automobiles are self-propelled vehicles used for travel on land. They are generally designed to transport a small number of passengers and may carry cargo. They are distinguished from trucks, which are designed primarily for the transportation of goods and are constructed with heavier parts, and buses (or omnibuses or coaches), which are large public conveyances that can carry many passengers and often additional cargo. The automobile is a complicated machine with many systems working together to power, control and steer the vehicle. These systems include the engine, drive train, suspension, brakes, steering system and electrical components. Research and development engineers work to improve the design of these systems and add new features that make cars safer, more comfortable, and more convenient to operate.

The development of the automobile has had a major impact on human society. It allows people to commute long distances, visit friends and family, go on vacation, and shop in a very flexible manner. It is also an important part of the infrastructure for the transportation of goods and services. Automobiles provide employment for millions of people. They also contribute to the economy by generating taxes and fees for the construction and maintenance of roads and parking spaces.

While the technology for the automobile existed as early as the 19th century, it was Henry Ford who made the automobile accessible to the middle class. He used the idea of the assembly line and pioneered mass production techniques that reduced the cost of the Model T to the point where it was affordable for the average American.

After the end of World War II automobile production increased dramatically as demand for them grew worldwide. Car makers began adding new features to post-war models such as automatic controls and power steering. They also produced larger vehicles that were more fuel efficient. The automobile has become an integral part of modern life and it is hard to imagine living without one.

Specialized automobiles are designed for different purposes, such as police cars, fire engines, ambulances and tow trucks. They are also used in road construction, fork-lifts at warehouses and as crane vehicles. Automobiles are also a source of controversy. Millions of people die in traffic accidents every year and their pollution is a serious problem for the environment. They also take up a lot of space in cities and are very expensive to maintain and repair. There are some people who oppose the use of automobiles and want to return to a time when walking or using bicycles was the main form of transportation.