Cryogenics is the study of low temperatures or the production of the same, and is often confused with cryobiology, the study of the effect of low temperatures on organisms, or the study of cryopreservation. Likewise, cryonics is the nascent study of the cryopreservation of the human body, is not an established science like cryogenics and is generally viewed with skepticism by most scientists and doctors today.
Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. These gases are held in special containers known as Dewar flasks. Dewar flasks are named after their inventor, James Dewar, the man who first liquified hydrogen. Everday vacuum flasks are a Dewar flask fitted in a protective casing.
Leiden, Netherlands is sometimes called "The Coldest Place on Earth", because of the revolutions in cryogenics that happened there. Some of these were the discovery of superconductivity by Heike Kamerlingh Onnes, the liquefaction of helium by Kamerlingh Onnes, and the solidification of helium by Kamerlingh Onnes' pupil, Willem Hendrik Keesom.