Automobiles have revolutionized society, allowing people to travel long distances easily. They are also a key economic force, driving the development of numerous ancillary industries such as steel and petroleum. In fact, they account for one of the largest sources of employment in the United States. The automobile is also a symbol of freedom and independence, allowing people to live where they choose.

The scientific and technical building blocks of the modern automobile go back several hundred years. Attempts at making motorcars run on steam, electricity or gasoline began in the late 1700s and early 1800s. By 1900, steam and battery-powered electric cars had a small share of the U.S. market, but were limited by poor performance and a lack of recharging stations.

Gasoline-powered cars eventually won out over steam and electric motorcars. By 1909, a German carmaker named Daimler had perfected a high-performance, four-cylinder gasoline-powered automobile. It weighed only fourteen pounds per horsepower and could reach fifty-three miles an hour. Although the Daimler was not yet a practical vehicle for mass production, it marked a major advance over previous automobiles.

In the United States, American Henry Ford introduced industrial manufacturing and assembly line techniques to his car factory in 1914, greatly reducing the cost of his Model T. This opened up the automobile market to middle-class Americans. By 1920, automobiles had become the dominant mode of transportation.

Currently there are over 1.4 billion passenger vehicles on the road, traveling more than three trillion miles (five trillion kilometers) each year. There are many different types of automobiles, ranging from basic sedans to luxurious sport utility vehicles. A new design is offered each year to take advantage of technological improvements.

Some of these include improved engine performance, more passenger comfort options and advanced safety features. Vehicle design depends to a large degree on its intended use. Automobiles built for off-road use require rugged designs and durable systems that are capable of withstanding severe overloads and extreme operating conditions. Vehicles built for highway cruising require more passenger seating and entertainment options, as well as optimized aerodynamics for higher speeds.

In addition, some vehicles are designed for special needs such as hauling cargo or transporting the disabled. These models typically have higher ground clearance, larger cargo capacities and more rugged body cladding.

Among the disadvantages of owning a car are the maintenance costs. Regular oil changes, tires and other repairs can add up quickly. Some areas have excellent public transportation, making it less expensive and environmentally friendly to rely on this form of transport rather than owning an automobile.

Another disadvantage is traffic congestion, which can make it difficult to get from point A to point B. This may result in missed appointments, lost time and wasted fuel. Traffic problems can be caused by physical bottlenecks (such as roads with too few lanes or insufficient traffic signals), road accidents, inclement weather, construction work and daily fluctuations in the flow of vehicles (such as morning and evening commutes). Some people may find that owning a car is not worth the hassle of dealing with traffic.