Automobiles are the world’s most common mode of transportation. In the United States alone people drive more than three trillion miles (five trillion kilometres) per year. They are often much faster than other forms of transport, and they allow people to go more places in one day than ever before. Automobiles are a major industry and contribute to the economy of many nations. They also provide jobs for millions of people, including those who work in car factories and at the gas stations and restaurants that serve travelers. They have also caused problems such as traffic congestion, air pollution and the loss of undeveloped land to parking lots.

The word “automobile” is derived from the Greek prefix “auto” meaning self and Latin words “mobilis” and “car” for carriage or vehicle. An automobile is a motor vehicle used to transport passengers and cargo on roads. It is similar to a truck/lorry and bus but has more in common with railway passenger trains. Automobiles are usually driven by a gasoline (petrol) or diesel engine. They run on four wheels and have a steering wheel and controls to control their direction. Most cars can be parked in a garage or on the street and most have seats for the driver and passengers.

Modern automobiles are complex machines with a large number of systems that interact with each other. These include the engine, transmission, electrical system and cooling and lubrication systems. The arrangement, choice and type of these components depends on the intended use of the car. For example, cars designed for off-road driving need rugged and simple systems that are resistant to severe overloads and extreme operating conditions. Other cars, such as sports models, need high-speed handling capabilities and optimized fuel efficiency.

In addition to the main systems of an automobile, there are a number of other important features. For example, most automobiles have doors to let the passengers in and out. These may be manual or automatic, depending on the model. A radio is another important feature of most automobiles, as are lights to indicate the status of the car and traffic signals. An alarm and a computer are sometimes included for safety.

Modern life would be inconceivable, or at least highly inconvenient, without access to a car. Millions of people depend on them for work, school and family activities. They also facilitate travel for recreation and shopping. In areas with limited public transportation options, it can make more sense than ever to have your own vehicle. However, the value of an automobile can be reduced by accidents and the need to pay for insurance, gas, oil and repairs. In some cases, it may not be financially practical to own a vehicle. In that case, it’s helpful to know what other modes of transportation are available. If you need to take a train or flight, for example, it’s best to plan ahead.