Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, and inert gas that heads the noble gas series in the periodic table. Its boiling and melting points are the lowestamong all the elements and it exists only as a gas except in extreme conditions. Helium is the second lightest element, after hydrogen, and is the second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined.

 

Helium was first discovered by French astronomer Jules Janssen and British astronomer Joseph Norman Lockyer in 1868 during a solar eclipse. The name "helium" comes from the Greek word 'helios', meaning sun, due to its presence in the sun's spectrum.

 

Helium has many important uses, including as a coolant for nuclear reactors and MRI machines, as a lifting gas for balloons and airships, and as a gas shield in arc welding and other industrial processes. It is also used in cryogenics to cool materials to very low temperatures and is an important component in the manufacturing of semiconductors and fiber optic cables.