An automobile, also referred to as a motor car or auto, is a four-wheeled vehicle used primarily for passenger transportation that is powered by an internal combustion engine using a volatile fuel. Modern automobiles are complex technical systems that employ subsystems designed to perform specific functions. They incorporate thousands of individual parts that have evolved from breakthroughs in existing technology or new technologies such as electronic computers and high-strength plastics and alloys of steel and nonferrous metals.

The automobile opened up new opportunities for people and transformed many areas of American life. People who previously had to depend on public transport were now able to travel more freely, and the ability to drive meant that rural dwellers could visit urban centers, and city-dwellers could escape to the countryside. It gave people the freedom to work, play, and socialize where they wanted, rather than being confined by the schedules of buses and trains.

Automobiles have shaped the economy, creating jobs and industries that are dependent on them. During the 1920s it was estimated that one out of every six jobs in America was related to the automotive industry. It was the backbone of a new consumer goods-oriented society, and a force for change in twentieth century America.

The first modern automobile was invented by Karl Benz in 1886. He built a two-seater, gasoline-powered car that used a four-stroke engine. It was the first to be produced commercially in large numbers. Other manufacturers experimented with steam and electric cars, but these were unable to compete with the reliability of gasoline-powered models.