Sex-determination system

A sex-determination system is the biological mechanism that decides whether an organism develops as male or female, typically involving specific chromosomes or environmental factors. In humans and many animals, this is controlled by sex chromosomes like X and Y, where males usually have XY and females have XX, though some species use entirely different systems based on temperature or other environmental cues. Essentially, it's nature's way of ensuring that organisms develop the physical and genetic characteristics needed for their role in reproduction.