A cell division is a cellular process called mitosis which includes the division of a parent cell and the production of two identical daughter cells. Mitosis is very important in the developmental stages since it helps the developing organism to fastly produce all the new cells needed.
When a person becomes an adult, the growth process has been completed, yet the mitotic divisions continue to happen. That is because the human body needs cell division to replace old, worn-out cells and dying cells. Also, cell division is needed to repair any injuries or destructions.