The liquefaction of a gas is the physical conversion of a gas to a liquid state. The liquefaction of natural gas is done for various industrial, commercial, and scientific reasons.For a gas such as carbon dioxide (CO2), liquefaction is easily done through a simple cooling process. However, the process of liquefaction for other gases can be very complex,involving very high pressure and low temperatures. In general, there are five types of liquefied gases: liquefied natural gas (LNG), natural gas liquids (NGL), liquefied Petroleum Gas (LPG), liquefied ethylene gas, and chemical gasses like chlorine and ammonia.In addition, other non-hydrocarbon natural gas elements and compounds such as oxygen (O2), argon (Ar), carbon dioxide (CO2), nitrogen (N), Hydrogen (H2), Helium (HE) can be liquefied in various freezing and cryogenic temperature ranges. The focus of this chapter is on LNG technology, including its history, value chains, processing, transportation,and more.