The science and technology of deep refrigeration processing occurring at temperatures lower than about 150 k. is the field of cryogenics. The name cryogenics is evolved from Greek word ?kryos? meaning icy cold. Phenomena that occurs at cryogenic temperatures include liquefaction and solidification of ambient gases; loss of ductility and embrittlement of some structural materials such as carbon steel; increase in thermal conductivity to a maximum value, followed by further decrease in temperature. Cryogenics is the low temperature (150 K) refrigeration. It explains the properties of cryogens used and their principles. Storage methods and handling techniques are covered. Cryogenics are applied in different fields of production, transportation, medicine, aerospace, physics research etc. Rocket propulsion is imparting force to a flying vehicle such as missile or spacecraft. Different types of rockets and their parts are explained. Cryogenics has future applications in many fields like superconductivity and propulsion fields. Cryogenics is being applied to variety of research areas; a few of which are: food processing and refrigeration, space craft life supporting system, space simulation, microbiology, medicine, surgery, electronics, data processing and metal working. Rocket propulsion is the process of imparting a force to flying vehicle such as a missile, by momentum of ejected matter. The matter, called propellant, is stored in the vehicle and ejected at high velocity. In chemical rocket, the propellants are chemical compounds that undergo a chemical combustion reaction releasing the energy for thermodynamically accelerating and ejecting the gaseous reaction products at high velocities. Chemical rocket propulsion is thus differential from other types of rocket propulsion which use nuclear, solar or electrical energy as their power source and which may use mechanism other than adiabatic expansion of a gas for achieving high ejection velocities.