Which element is most abundant in the universe?

Hydrogen is the most abundant element in the universe, making up about 75% of its elemental mass. It is the simplest and lightest element, consisting of one proton and one electron, and it plays a fundamental role in the formation of stars and galaxies. Hydrogen is primarily found in stars, where it undergoes nuclear fusion to create helium, releasing energy in the process. This abundance is a result of hydrogen being one of the first elements formed during the Big Bang, leading to its widespread presence throughout the cosmos.

While other elements like helium and oxygen are also prevalent, they exist in smaller quantities compared to hydrogen. Helium is the second most abundant element but constitutes only about 25% of the elemental mass of the universe. Carbon, although essential for life and found in various cosmic structures, is much rarer than both hydrogen and helium.