The automobile is a wheeled passenger vehicle, usually four-wheeled, powered by an internal combustion engine with a volatile fuel. Its design uses complex mechanical systems with specific design functions and a variety of components.
The technological building blocks of the modern automobile go back hundreds of years. Leonardo da Vinci drafted theoretical plans for such a machine during the Renaissance, and in the 1800s steam cars and a variety of electric vehicles were available. By the turn of the 20th century gas-powered cars were widespread.
Automobiles have become a symbol of individual freedom and social change. They have allowed women to work outside the home and participate in public life, including politics. They have given people the ability to travel long distances quickly and without worry of getting lost or arriving late. They have also enabled people to get around more quickly and inexpensively than they could by bus, train or taxi, especially when traffic is heavy.
However, automobiles are often a source of pollution and can cause accidents that hurt or kill people. They can increase the cost of living by forcing people to spend more on gasoline and maintenance. Their higher unit profits can also come at a high social cost in the form of increased air pollution and a drain on dwindling world oil supplies. Consequently, some cities are developing mass transit systems to replace the automobile with buses, trains and trams that offer faster, cheaper, more environmentally friendly transportation.