Here's a breakdown:

* Hydrogen (H) is the most abundant element in stars, making up about 70-75% of their mass.

* Helium (He) is the second most abundant element, making up about 24-28% of their mass.

* Trace Elements: Stars also contain tiny amounts of other elements like carbon, oxygen, nitrogen, and iron. These elements are formed through nuclear fusion processes within the star.

How stars are formed:

Stars form from giant clouds of gas and dust called nebulae. Gravity pulls these clouds together, and as the material collapses, the core heats up. Eventually, the temperature and pressure become so intense that nuclear fusion begins, where hydrogen atoms fuse to form helium and release enormous amounts of energy. This energy is what makes stars shine!