Stem cells are cells that can indefinitely divide and renew specialized cells. Stem cells can be classified as embryonic or somatic. Embryonic stem cells become every cell in the human body. Adult stem cells are later-stage cells that are found in specific tissues of the body and work to replenish and repair those tissues throughout the life of the organism. 

What is a Stem Cell?  Check out this video from our friends at the Stem Cell Network.