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The Noble Gases form Group 18 of the Periodic Table of elements. There are seven noble gases known to date. Older American textbooks call this group VIIIA while in the older European convention it was group VIIIB. Group 18 is the preferred International Union for Pure and Applied Chemistry (IUPAC) designation. Only one noble gas is a man-made element. All of the noble gases have a complete compliment of electrons in their outer electron shell. This means they have a very stable electron structure.

The Scottish chemist Sir William Ramsay discovered argon, neon, krypton and xenon during the eighteenth century. Sir William Ramsay also was the first to detect helium on earth although Pierre-Jules-Cesar Janssen discovered it spectroscopically within the sun before he discovered it on earth. Friedrich Ernst Dorn discovered radon, the only naturally occurring radioactive noble gas, in 1900. Ununoctium is a man-made "super heavy" noble Gas produced in 2002 at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. To produce a few atoms of this element they bombarded a target of californium-294 atoms with ions of calcium-48.

Because of their stable electron structure, noble gases were believed to be totally inert and unable to produce compounds with any other elements. This is no longer true, as some of them have been found to produce a few compounds, usually with one of the highly reactive elements of the Halogen Group such as fluorine. Often these compounds are only stable under specific conditions. Argon fluorohydride will decompose at temperatures above minus 245 C (28 K, minus 409 F). Therefore, for all practical commercial uses, the noble gases are inert.

Because they are so inert, some of the noble gases are of use in the provision of atmospheric shields. Such shields are of use in protecting the production of semi conductor crystals (germanium) and reactive elements (titanium). They are also in use for the protection of some arc welding and cutting processes. The gases commonly used for such shielding purposes are argon and helium. They are also of commercial use as liquid refrigerants.

While the noble gases only form a small percentage of the earth's atmosphere higher percentages of some exist in the universe. Helium is the second most abundant element in the universe after hydrogen yet the earth's atmosphere contains only 0.0005% of the gas. Neon, which is the fourth most abundant element in the universe, forms only 0.0018% of the earth's atmosphere.

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