Crude oil is unrefined petroleum product composed of hydrocarbon deposits and other organic materials. A type of fossil fuel, crude oil can be refined to produce usable products such as gasoline, diesel and various forms of petrochemicals.

Crude oil is a liquid fuel source located underground. It was created when the remains of prehistoric algae was heated under pressure by the earth itself over millions of years. That's why it's considered nonrenewable.

WTI (West Texas Intermediate) crude oil is of very high quality because it is light-weight and has low sulphur content. For these reasons, it is often referred to as “light, sweet” crude oil.

These properties make it excellent for making gasoline. That's why it is the major benchmark of crude oil in the Americas.

Brent Blend is a combination of crude oil from 15 different oil fields in the North Sea. It is less “light” and “sweet” than WTI but still excellent for making gasoline.

It is refined in Northwest Europe and is the primary benchmark for crude oils in Europe or Africa.

Shale oil is crude oil that lies between layers of shale rock. The rock must be broken up to allow access to the layers of oil.

Oil shale is oil that's derived from kerogen. That's an early form of oil that requires more pressure and heat to become usable fuel.

OPEC controls almost 40 per cent of the world's crude oil, accounts for about 75 per cent of the world's proven oil reserves, and exports 55 per cent of the oil traded internationally.