Automobiles, also known as cars or automobiles, are motor vehicles that run primarily on roads and transport people rather than cargo. They typically have four wheels, seat one to eight people, and are powered by an internal combustion engine.

Invented in the late 1800s, automobiles are widely considered to be among the most significant inventions of modern times. They greatly improved upon the horse-based travel that preceded them. Their development allowed people to travel farther distances for work, explore new parts of their communities, and expand their social circles. It also enabled them to reach medical care much more quickly, saving lives and making life much easier for millions of people.

A car is a complex technical system that consists of many subsystems designed to perform specific functions. The most basic elements are the chassis, bodywork, powertrain, and electrical equipment. The chassis is the frame that supports the rest of the vehicle, and the powertrain is the engine, transmission, and differential that drive the wheels.

Most contemporary cars use an internal combustion engine powered by gasoline, diesel fuel, kerosene, or other volatile fuel. The engine is usually mounted on the chassis and is driven by a belt or chain that connects to a crankshaft. The crankshaft in turn drives the wheels.

Automobiles have a long history, and their design continues to evolve. During the early days of their development, hundreds of small manufacturers competed to gain market share. This created a rapid pace of innovation. In the 1920s, a number of key innovations were made, including electric ignition and the electric self-starter (both by Charles Kettering), independent suspension, and four-wheel brakes. However, by 1960, the industry was reaching maturity and growth slowed.

In the early 1970s, environmental and safety concerns began to rise, resulting in the introduction of government legislation such as the National Traffic and Motor Vehicle Safety Act and California emissions standards, which significantly altered the automotive landscape. Manufacturers responded by increasing the emphasis on safety features and adding emission control technologies. By the 1980s, most automobiles were produced by large multinational companies such as Ford, General Motors, and Chrysler.

Although cars are still the most common form of transport in the world, there is an ongoing effort to develop alternative forms of transportation that are safer and more environmentally friendly. Some of these alternatives include hybrid electric vehicles, which combine the efficiency of an internal combustion engine with a battery-powered electric motor, and hydrogen fuel cells, which convert chemical energy into electricity without producing harmful waste products. There are also research programs focused on high-speed rail technology, which could allow passengers to travel between cities in a fraction of the time it takes to drive between them. In addition to these technological advances, there is a continuing focus on improving fuel economy through lightweight materials and aerodynamic design. This will reduce both the weight of the vehicle and the amount of gasoline required to propel it.