Processing crude oil to make petroleum products (including gasoline, Naphtha, kerosene, diesel, and heavy oil) is called petroleum refining.

A plant, equipped with the facilities for crude oil refining, is called a refinery, and the enterprises, engaging in oil refining, are collectively called the petroleum industry.
The main process in petroleum refining is to distill crude oil and separate it into different cuts. Crude oil is first distilled at the standard atmospheric pressure and separated into gasoline and light-cut naphtha. This operation is called topping, and it is a main process in petroleum refining.
Refineries are divided into a refinery, producing only fuel oil; a complete refinery, producing everything from fuel oil to lubricants; and a simple refinery, producing naphtha for petrochemical plants and heavy oil for thermoelectric power plants. Also, there are chemical refineries that produce petrochemical feedstock like olefin and aromatic hydrocarbon from crude oil, and very little petroleum products.