Automobiles are one of the most important ways to get around in a modern world. They are used by 243 million people worldwide, and more than 60 million new cars are produced each year. Most definitions of automobiles describe them as four-wheeled vehicles designed primarily for passenger transportation and propelled by an internal combustion engine powered by volatile fuel. However, trucks, buses, limousines, and vans are all also considered to be automobiles despite being different in design from the typical sedan.
The history of the automobile has been a long and complicated one. Exactly who invented the first true car is a matter of dispute, but some of the most significant innovations in automobile technology occurred in the 1800s and early 1900s, with gas-powered cars gaining dominance by 1910. One of the most significant milestones came in 1908 when Henry Ford introduced his Model T, which greatly simplified vehicle design and made automobile ownership affordable for the general public.
After that, automobile technology progressed rapidly in response to the competition among many small manufacturers. The most significant advances included the electric starter and ignition (invented by Charles Kettering for Cadillac Motor Company in 1914-1915), independent suspension, and four-wheel brakes. By the 1920s automakers had consolidated into the big three of Ford, General Motors, and Chrysler. As the industry went through a period of market saturation and technological stagnation in the 1930s, consumers began to express concern about nonfunctional styling, safety issues, and ecological aspects such as pollution and draining of the world oil reserves.