Cells divide as a way of reproducing or growing or to create sex cells. Cells can only reach a certain size due to a lack of balanced growth between their parts, so they have to divide once they reach a certain point. Sex cells, such as eggs and sperm, are only created through specialized cell division.
Cell division is a form of reproduction, but each resulting cell in normal cell division is identical to the original. Normal cell division is called mitosis, and this results in two identical cells. These cells continue life and perform the same functions as the original cell. They grow and eventually undergo division themselves. This is the type of division for most cells.
The other type of cell division is called meiosis, and it is how the body produces eggs or sperm. The process is the same for both males and females. A single egg goes through many of the same stages that are in mitosis, but there are a couple of key differences. The DNA within the cells are mixed up so the end cells are genetically diverse. The division goes one step further than mitosis, resulting in four cells. The resulting sex cells would be impossible without cell division.