What is the approximate chemical composition by mass with which all stars are born?

All stars are primarily composed of hydrogen and helium, with approximately 74% of their mass being hydrogen and about 24% helium. The remaining 2% consists of trace amounts of heavier elements, often referred to as "metals" in astronomical terms, such as carbon, oxygen, and nitrogen. This composition reflects the primordial material from the Big Bang and subsequent stellar processes that enriched the interstellar medium.