This is Mitosis, which occurs with all nucleated somatic (body) cells, but not in germ (sex) cells.
Germ cells, aka gametes, on the other hand, undergo Meiosis, a process of nuclear cell division whereby 1 parent cell gives rise to 4 daughter cells. These daughter gametes, either sperm or egg cells, all have 1/2 the number of chromosomes as the original parent, termed "haploid." The genes of these gametes were also randomly assorted and crossed-over, allowing a shuffling of their chromosomes' genes.