The term 'Resource Measured in Barrels' refers to OIL, which is a three-letter word. OIL is a naturally occurring, flammable liquid found in geological formations beneath the Earth's surface. It is a fossil fuel, meaning it was formed millions of years ago from the remains of dead organisms. OIL is used for a variety of purposes, including as a fuel for vehicles, as a lubricant, and as a raw material in the chemical industry. It is measured in barrels, which is a unit of volume equal to 42 US gallons.