A stem cell is an unspecialized cell that can undergo cell division to produce one identical daughter stem cell and one specialized daughter cell. The daughter cell can go on to differentiate to become a cell belonging to a distinct organ system that takes on the structure and function of a cell in that system. They are most commonly found in early embryos, where the cells have not yet started becoming specialized. Although they are also found in adults, adult stem cells are few in number and do not have the ability to differentiate into all cell types. Stem cells have the potential to be used in medicine to repair damaged or diseased organs or cells.