Nails are simply a specialized extension of skin. They are dead keratinaceous/epithelial material that is firmly attached to richly vascular nail beds. Because they grow rapidly in healthy people fingernails up to .1 mm daily, toenails less quickly they can provide fairly good recent history of physiological imbalances throughout the body. Also, changes in the vascularity of the nail bed will change the color of the nails and indicate other clinical problems in various areas of the body.