Gaseous element, first observed spectroscopically in the sun during a solar eclipse in 1868. Its noncombustibility and buoyancy make this extremely unreactive inert Gas the most suitable of gases for balloons and airships.

Deep-sea divers often breathe a helium-and-oxygen mixture because helium is less soluble in human blood than nitrogen, its use reduces the risk of the bends.

Liquid helium is essential for low temperature work Cryogenics, Superconductivity. Helium is also used in arc welding and gas-discharge lasers.

Abundant in outer space, helium is the end product of fusion processes in stars.