Automobiles are motor vehicles designed for passenger transportation on land. They usually have four wheels and are fueled by gasoline, a liquid fuel. Cars are one of the most widely used of modern technologies and are a primary means of transportation for millions of people around the world.

The invention of the automobile ushered in an era of unprecedented mobility and individual freedoms that have transformed the lives of people worldwide. It also gave rise to the growth of many ancillary industries and helped to change the way people live, work, and play. The automobile has become a symbol of America and its consumer culture, as well as a global industry that is responsible for many jobs.

Modern life would be unthinkable without cars, with their convenience and ability to carry a person and his or her belongings from place to place. The number of automobiles in the world is now more than 1.4 billion, and Americans drive over three trillion miles per year.

There are many different types of automobiles, each suited for a particular type of driving and use. Some are built for off-roading, able to traverse rugged terrain and extreme weather conditions. Others are built for speed, allowing drivers to travel at high rates of speed over long distances. Still others are specialized for hauling heavy loads or providing comfort on long journeys.

The first automobiles were powered by steam. Later they were powered by electricity, and then by internal combustion engines that burn petrol or diesel. The engines were based on the principles of the steam engine, with pistons moving in cylinders by an external force. Various designs were tried, including steam buses and phaetons, but the real breakthrough came with the introduction of the internal combustion engine, in which the fuel is burned inside the engine and the power generated causes the pistons to move.

By the 1920s the automobile had transformed American life. It became the backbone of a new consumer goods-oriented society and the major customer for steel, petroleum, and other industrial products. Its demand led to the development of new, more efficient production techniques in automotive factories. For example, Henry Ford introduced the assembly line in 1913, enabling workers to perform one task at a time as parts passed by on conveyor belts.

Despite their utility, automobiles have some disadvantages. They pollute the atmosphere with carbon dioxide, a greenhouse gas, and they consume large amounts of energy. Moreover, they are expensive to operate and maintain. However, for most people, the benefits of having a car outweigh these problems. In addition, people can use their cars to commute to work or school, shop for food and other necessities, and visit friends and family. They can also use them to take part in recreational activities, such as going on road trips and attending concerts.