The normal healthy skin has a nice epidermis with a smooth cornified, or outer, a layer that acts as a good barrier to water and environmental injury. Skin color and tone is even and unblemished. Components such as collagen (which provides skin firmness), elastin (which supplies skin elasticity and rebound) and glycosaminoglycans or GAGs (which keep the skin hydrated) are all abundant.
With age, skin cells divide more slowly, and the skin’s inner layer, called the dermis, begins to thin. That starts to undo skin’s stretchiness and structure.