Life has evolved from simple stages to more complex ones, and so have the reproduction mechanisms.
Initially the reproduction was a replicating process that consists in producing new individuals that contain the same genetic information as the original or parent individual.
Sexual reproduction in eukaryotes is a process whereby organisms form offspring that combine genetic traits from both parents.
Chromosomes are passed on from one generation to the next in this process.
The ZW sex-determination system is shared by birds, some fish and some crustaceans.
Disregarding intermediates, the basic distinction between asexual and sexual reproduction is the way in which the genetic material is processed.