Helium is a noble gas represented by the symbol He. It is colorless, odorless, and non-reactive. Helium exists as a single atom (monatomic gas), not as He₂.

Helium is lighter than air, which is why it is used in balloons and airships. It does not burn and is very safe. Helium is also used in medical equipment, MRI scanners, and deep-sea diving tanks.

Helium is the second most abundant element in the universe and is produced during nuclear reactions in stars.