Nature has provided us with a wonderful outer surface, the skin. We humans are fascinated with our epidermis and hair. We spend an exorbitant amount of time and money on skin and hair maintenance. We try hard to keep it soft, smooth, radiant, tan or pale, clean or made-up. We try to remove hair from some areas as hard as we try to keep it on others. Only when our skin is afflicted by disease, burns, wounds, or scratches is it apparent that this amazing outer shell protects us from dehydration and infections. To perform this crucial protective function and to be able to respond to injuries, skin needs to undergo self-renewal to repair damaged tissue and to replace old cells. For this formidable task, skin depends on stem cells. Stem cells have the ability to self-perpetuate and to give rise to differentiating cells that constitute one or more tissue types.