* Hydrogen makes up about 70% of the mass of a typical star.

* Helium makes up about 28% of the mass.

* The remaining 2% is comprised of heavier elements like carbon, oxygen, neon, iron, and so on.

This composition is a result of the Big Bang, which created a universe primarily made of hydrogen and helium. Stars are born from clouds of gas and dust that are mainly composed of these two elements.