What is Natural gas ? Natural gas is a gaseous fossil fuel consisting primarily of methane. Natural gas is found in oil fields and natural gas fields, and in coal beds. When methane-rich natural gas are produced by the anaerobic decay of non-fossil organic material, these are referred to as biogas. Sources of natural gas include swamps, marshes, and landfills (see landfill gas), as well as sewage sludge and manure natural gas by way of anaerobic digesters, in addition to enteric fermentation particularly in cattle. Natural gas is often informally referred to as simply gas, especially when compared to other energy sources such as electricity. Reference :Wikipedia, the free encyclopedia