Helium (He) is a chemical element and a colorless, odorless, tasteless, inert gas. It has the smallest atomic radius of any element and the second-lowest atomic weight. It is lighter than air.

Most people know that helium is used as a lifting gas in blimps and party balloons, but they can't name another way in which it is used. The number one use of helium is as a cooling gas for magnetic resonance imaging (MRI) machines used in medical facilities. Other important uses of helium include: a protective gas for welding, an inert gas for controlled atmosphere manufacturing, a fugitive gas used for leak detection, and a low-viscosity gas for pressurized breathing mixtures.