Stem cell is a cell that has the ability to continuously divide and differentiate into various other kinds of cells or tissues.
Stem cells give rise to various cells when they acquire special function through a process called cellular differentiation. This ability allows them to replace cells that have died or are damaged. They also maintain the normal turnover of regenerative organs such as blood, skin, and intestinal tissues. They are found in fetuses, embryos, and certain adult tissues.
With this ability, they have been used to replace defective cells/tissues in patients who have certain diseases or defects.