Why does the formation of an iron ($ ext{Fe}$) core signify the end of energy generation through fusion in a star?

Answer

Fusing iron nuclei consumes energy rather than releasing it

Iron represents a crucial boundary because, unlike lighter elements, the nuclear reaction of fusing iron requires an input of energy, meaning fusion can no longer counteract the star's gravitational collapse.

Why does the formation of an iron ($	ext{Fe}$) core signify the end of energy generation through fusion in a star?
ElementastronomystarFusionnucleosynthesis