The standard unit of oil measurement in the U.S. oil industry. A barrel equals 42 U.S. gallons, or 159 liters. [in some countries oil is measured using the metric system; volumes in liters or weights in metric tons.

In the oil industry, a barrel is 42 US gallons, approximately equal to 159 litres.... more on: Barrel of oil

One stock tank barrel of oil or natural gas liquids, with volumes expressed in standard 42 US gallon barrels or 34.972 Imperial gallon barrels.

a commodity that can only contribute to the economy when spent or sold

a global commodity from the moment of its discovery, whether it lies in Alaska, Texas, Saudi Arabia, Indonesia, Mexico, Norway, Angola, or Venezuala