An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as naphtha, gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas. Oil refineries are typically large, sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units. In many ways, oil refineries use much of the technology of, and can be thought of, as types of chemical plants. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot (tank farm) at or near an oil refinery for storage of bulk liquid products.

An oil refinery is considered an essential part of the downstream side of the petroleum industry.

Raw or unprocessed crude oil is not generally useful in industrial applications, although "light, sweet" (low viscosity, low sulfur) crude oil has been used directly as a burner fuel for steam vessel propulsion. The lighter elements, however, form explosive vapors in the fuel tanks and are therefore hazardous, especially in warships. Instead, the hundreds of different hydrocarbon molecules in crude oil are separated in a refinery into components which can be used as fuels, lubricants, and as feedstock in petrochemical processes that manufacture such products as plastics, detergents, solvents, elastomers and fibers such as nylon and polyesters.

Thomas Leo "Tom" Clancy, Jr. (born April 12, 1947) is an American author, best known for his technically detailed espionage, military science, and techno thriller storylines set during and in the aftermath of the Cold War, along with video games on which he did not work, but which bear his name for licensing and promotional purposes. His name is also a brand for similar movie scripts written by ghost writers and many series of non-fiction books on military subjects and merged biographies of key leaders. He is Vice Chairman of Community Activities and Public Affairs, as well as a part-owner, of the MLB Baltimore Orioles.

Clancy was born in Baltimore, Maryland. He attended Loyola Blakefield in Towson, Maryland, graduating with the class of 1965. He then attended Loyola College in Baltimore, graduating in 1969. Before making his literary debut, he spent some time running an independent insurance agency. This agency thrived for a few years before joining a group of investors.

Clancy and his first wife Wanda married in 1969, separated briefly in 1995, and permanently separated in December 1996. Clancy filed for divorce in November 1997, which became final in January 1999.