How do we use the petroleum?

To be of use to us, the crude oil must be “fractionated” into its various hydrocarbons. This is done at the refinery.
 
Oil can be used in many different products, and this is because of its composition of many different hydrocarbons of different sizes, which are individually useful in different ways due to their different properties. The purpose of a refinery is to separate and purify these different components. Most refinery products can be grouped into three classes: Light distillates (liquefied petroleum gas, naphtha, and gasoline), middle distillates (kerosene and diesel), and heavy distillates (fuel oil, lubricating oil, waxes, and tar). While all of these products are familiar to consumers, some of them may have gained fame under their refined forms. For instance, naphtha is the primary feedstock for producing a high octane gasoline component and also is commonly used as cleaning solvent, and kerosene is the main ingredient in many jet fuels.