Natural Gas (NGAS) is a fossil fuel generated from animals and plants buried under the ground and exposed to hot weather and pressure. Natural gas is used primarily for domestic purposes, such as cooking. It is also used as a power source in industrial manufacturing and agriculture. Natural gas prices are constantly changing and are contingent mostly on stockpiles, production issues, economic growth, weather conditions, crude oil prices, and most recently, coal. Natural gas is generally measured in MMBtu, with 1 MMBTu equalling 1 million BTU (British Thermal Units).