What is fractional ditillation and oil refining?

It's when crude oil is heated in a pressure vessell. At different tempertures you get different products. The LPG's go to the top and are collect. the next lower level collector is light fuels like gasoline, then the next lower level is Diesel and Jet fuel, next lower is kerosine and at the bottom collector is heavy Fuel Oil. the heavier the product the higher the temperture needed. The last product of the process is pure nasty carbon called ';Coke'; which is used in steel plants for use in making high carbon steel. Every drop of oil has useable product.