The first commercial oil wells were drilled in the mid-1800s, tapping into a vast new resource of energy. Petroleum was a fossil fuel. And, at first, its most important product was kerosene, which was used for lighting and heaters. In 1847, inventors developed chemical techniques to extract kerosene from petroleum. These techniques led to other developments, such as precision machinery and the internal combustion engine, which led to automobile and airplane technologies. With the introduction of automboiles in the early 1900's, gasoline became a more important product than kerosene.