What is crude oil, and what is used for ?

Crude oil is pumped from the ground in the Middle East (e.g., Saudi Arabian Arab Light), West Africa (e.g., Nigerian Bonny Light), the Americas, and Asia (Russia), pumped into ships called tankers, and sailed across the ocean to oil refineries on the Delaware River. Refining is the complex series of processes that manufactures finished petroleum products out of crude oil. While refining begins as simple distillation (by heating and separating), refiners must use more sophisticated additional processes and equipment in order to produce the mix of products that the market demands. Generally, this latter effort minimizes the production of heavier, lower value products (for example, residual fuel oil, used to power large ocean-going ships) in favor of middle distillates (jet fuel, kerosene, home heating oil and diesel fuel) and lighter, higher value products (liquid petroleum gases (LPG), naphtha, and gasoline).

(Source : http://www.ceoe.udel.edu/oilspill/crudeoil.html)