Petroleum: A naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface. It is commonly refined into various types of fuels.
OPEC (Organization of Petroleum Exporting Countries): An intergovernmental organization of 13 nations founded in 1960 to coordinate and unify petroleum policies among member countries.
Fracking: A process used in nine out of 10 natural gas wells in the United States, where millions of gallons of water, sand and chemicals are pumped underground to break apart rocks and release gas.