Seen in a cross-section, the skin has two main levels, the dermis and the epidermis. The dermis is the lower, thick foundation layer containing blood vessels, hair roots, sweat glands, and nerves. The top layer, or epidermis, consists of several layers of cells pushing their way to the surface in succession. As they do this, they become flatter, harder and dryer. By the time they reach the skin's surface they are dead cells and will eventually be sloughed away.
Humans truly are thin-skinned creatures.
Even so, skin is amazingly tough, containing two of the strongest substances in the human body are collagen and elastin. This substance is keratin. The protein bonds that form collagen, elastin and keratin are incredibly strong, but not unbreakable. Many skin care products contain acids or bases that are outside the normal pH range of healthy skin, and when such products are used every day, as are most cleansers, real damage to the skin can result. Most cleansers will rid the skin of dirt and oils and flush away disease-causing bacteria and fungal spores.