Helium (He) is the Element with atomic number 2, symbol He. Its most common Isotope and has mass number 4, but mass number 3 is also stable. It is the second most common element, about 24% of the observable universe by mass (Helium Abundance).
A bit is the result of nuclear Fusion of Hydrogen in stars, but most helium was formed in conditions shortly after the Big Bang. The initially-very-hot universe descended through Temperatures that produced a particular ratio of neutrons and protons, which at a cooler temperature, combined into low-mass isotopes, including a very stable helium isotope (mass number 4), much of which remained as the temperature cooled further.
Helium has a Metastable State of Excitation with one electron excited and of opposite the typical spin. It can remain in this state for a couple of hours and on relaxing, produces an Emission Line of about 80830 Angstroms.