Liquified Natural Gas (LNG) is a clear, colorless liquid, made by cooling natural gas to about -163 degrees centigrade. Natural gas is composed mainly of methane and ethane, and can be used as a fuel.
Natural gas is extracted from oil and gas wells, and is also found in wetlands and from anthropogenic sources that include landfills and agricultural operations. When cooled and liquefied, it takes up only a tiny fraction of the volume of the gaseous form, so can be transported efficiently.