Automobiles are a very important source of transportation in many countries around the world. They can carry more people than a bicycle or a bus and can travel long distances much faster than walking. They can also reach places that public transport cannot, such as mountainous areas or deserts. However, an automobile does cost more than a bicycle or a bus and uses up large amounts of fuel. In modern times the automobile has become an essential part of our daily lives, taking us to work, school, shopping and leisure activities.

The modern automobile is a complex technical system with many subsystems that have specific design functions. The main parts of an automobile are the chassis, engine, transmission and wheels. The engine is a small internal combustion engine powered by a volatile fuel. The fuel is burned in a cylinder under high pressure, and the combustion causes a piston to push down on a crankshaft. The crankshaft turns the wheels to move the car forward or backward.

Early cars used a variety of fuels, but the most common is gasoline (or petrol in some countries). The burning of the fuel gives the engine energy to turn the wheels and drive the vehicle. Most engines use a transmission to change the speed of the wheel rotation, and this can be controlled to make the vehicle go fast or slow. Some modern cars run on electric power instead of gasoline, but this is a much newer technology.

Many inventors have contributed to the development of automobiles. Karl Benz is usually credited with inventing the modern automobile, although he did not build the first working model until 1886. He used a four-stroke type of internal combustion engine and built the Benz Patent-Motorwagen. He began to manufacture and sell his vehicles in Germany in 1888.

Other early inventors developed different types of engines that could be used to propel a car. These included steam, electric and internal combustion engines. Steam engines could go very quickly, but were bulky and dangerous to operate. Electric motors were much lighter and less expensive, but they could only be used at low speeds, and the batteries had a very limited life span.

The automobile became a key force for change in twentieth-century America as it transformed society from an agricultural to a consumer goods-oriented culture. It also revolutionized the economies of many ancillary industries, including petroleum and steel. In 1982, the automobile was the number one producer of industrial value and provided more than one out of six jobs in the United States.