Almost all oil and natural gas are found deep underground in tiny holes in rocks. Millions of years ago, the remains of plants and animals decayed and built up in thick layers. Over time, this organic material changed into coal, oil and natural gas.
Oil is a smelly liquid that is usually found in underground areas called reservoirs. Crude oil comes in many forms. Usually it is black, but green, red or brown oils are not uncommon. After crude oil is removed from the ground, it is sent to a refinery where different parts of the crude oil are separated into usable petroleum products.
Some products made from petroleum include gasoline, diesel, crayons, dishwashing liquids, deodorant, tires, plastics etc.