Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.

Its boiling point is the lowest among all the elements and has no melting point at standard pressure. After hydrogen, it is the second lightest and most abundant element in the observable universe. It is present at about 24% of the total elemental mass, more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter due to the very high nuclear binding energy (per nucleon) of helium-4, concerning the next three elements after helium.

The biggest current usage of helium is for human cryogenics. The volume of helium spent on cryogenics was about 420 million liters. The chief cryogenic applications explained in this part are magnetic resonance imaging (MRI), semiconductor chip processing, and huge-scale and little-scale foundation analysis that needs helium temperatures.