A car is a wheeled automotive vehicle used for the transportation of goods or people. Cars primarily run on roads, and they can seat one to eight people. Cars provide on-demand transportation, mobility, independence, and convenience. The Model T, manufactured by the Ford Motor Company and rapidly adopted in the US in the early 20th century, replaced animal-drawn carriages; it was one of the first cars accessible to the public. Today there are around one billion cars in use, and with their continued increase, new technologies such as plug-in hybrids and the use of alternative fuels are quickly emerging. Autonomous cars, open source development, and car sharing are further developing to improve the future use of automobiles.