Automobiles are vehicles used for transporting passengers or freight on land. They consist of four to eight tires and are powered by internal combustion engines or electric motors. Automobiles are a major mode of transport today, and the branches of engineering that deal with automobiles are known as automotive engineering.
The advent of the automobile has had a profound impact on American society, changing lifestyles in many ways. It enabled urban dwellers to rediscover the countryside, and rural people to shop in towns. It gave teenagers more freedom of movement and helped develop more relaxed dating habits among couples. And it opened new opportunities for businesses, such as gas stations, hotels and motels, restaurants and fast food shops, and recreation parks and amusements. It also brought new laws and government requirements, including safety features like seatbelts and driving licenses.
In addition, it has brought harm to the environment, from exhaust pollution to the loss of undeveloped land for use as highways. In the late 20th century, modern life seemed inconceivable without access to an automobile.
The automobile was the result of the invention of the internal combustion engine, a device that converts the energy of a fuel, such as gasoline, diesel or kerosene, into mechanical power to turn the wheels of an automobile. It is a very versatile engine, as it can be used to propel both passenger and freight cars, and can also be used in locomotives and ships.