Meiosis is the nuclear division of diploid cells into haploid cells, which is a necessary step in sexual reproduction.
In meiosis I, the first round of meiosis, homologous chromosomes exchange DNA and the diploid cell is divided into two haploid cells.
During meiosis II, the sister chromatids within the two daughter cells separate, forming four new haploid gametes.
Mitosis and meiosis share some similarities, but also some differences, most of which are observed during meiosis I.
The genetic diversity of sexual reproduction, observed in most eukaryotes, is thought to give species better chances of survival.
The main categories of sexual life cycles in eukaryotic organisms are: diploid-dominant, haploid-dominant, and alternation of generations.