Automobiles are self-propelled vehicles that travel on land and have four wheels. They are powered by an internal combustion engine (usually gasoline, but can also be electric or fuel cell) and carry a number of passengers for personal transportation. Automobiles are also used for commercial purposes, such as delivery and haulage.

The automobile revolutionized modern life by allowing individuals to move rapidly and independently from one place to another, opening up new economic, social, and recreational opportunities. Its widespread use spawned many new industries and services such as gas stations, motels, fast food restaurants, and leisure activities like golf and tennis. Automobiles can go much faster than walking or riding a bicycle, can hold more people than a horse-drawn carriage, and can reach places that are inaccessible to other forms of transportation.

However, automobiles can also damage other property and hurt or kill people if they crash. The soaring rate of automobile accidents and injuries in the early twentieth century prompted public concern and stimulated debate about what could be done to reduce them. Physicians, safety advocates, engineers, and journalists offered many answers ranging from strict driver regulations to redesigning automobiles to improving the driving environment.

Modern automobiles are very complex systems, and their design depends to a large extent on their intended use. Automobiles for off-road use must have simple and rugged designs, while those designed for high-speed performance need advanced powertrain and chassis technologies. Many of the latest cars are equipped with safety features that are mandated by law or otherwise available as options.

Most people own at least one automobile, and some have more than one. An automobile is a convenient way to get around, especially in large cities with extensive road networks. It is generally more convenient than using a train, bus, or bike, and can be faster and cheaper than taxis or ride-sharing services. It also allows the owner to control when and where they travel, which is not always possible with other types of transportation.

Some people prefer to forgo the expense of owning their own automobile, choosing instead to rely on public transit, ride-sharing services, or carpools. But for many Americans, modern life seems inconceivable — or at least highly inconvenient — without an automobile. Even if you don’t drive, having access to a car can be invaluable for shopping, running errands, and getting to work on time. And of course, part of the fun of owning an automobile is driving it yourself. If you don’t want to be a slave to your car, check out these tips for driving responsibly.