Most stars we see are burning Hydrogen, possibly helium, in a process of gravity well driven nuclear fusion.  This fusion results in heavier atomic particles and some waste that we see as radiation (light, heat, various forms of EM energy).<p>I am not an astrophysicist, nor am I an expert in the early universe, but I recall that the prevailing theories of our time are that somehow the universe came in to being with predominantly hydrogen atoms.  These combine through fusion in what we call stars to form denser matter.  This process continues until the result of combining the elements reaches a limit.  I believe that iron happens to be that limit if I recall correctly.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Iron_peak" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Iron_peak</a><p>Describes what I recall reading&#x2F;hearing many years ago.