Harmless bacteria protect the skin surface from harmful bacteria, and the thin layer of fatty acids on the skin is also bactericidal. In addition to its protective properties, the skin’s rich nerve supply allows it to transmit a variety of sensations such as touch, pain, temperature, pleasure, and pressure to the central nervous system. Vitamin D, a fat-soluble vitamin necessary for calcium and phosphate absorption, is manufactured when the skin is exposed to ultraviolet rays. If injury occurs the skin can quickly regenerate.

At birth the skin is immature, fragile, and thin. There is little subcutaneous tissue beneath it, making the newborn susceptible to heat loss and vulnerable to the absorption of harmful chemicals. Eccrine glands, which help regulate body temperature by producing sweat, do not mature until ages 2 or 3 years. These glands are found in the highest numbers in the palms, forehead, and soles of the feet. Apocrine glands are located in the groin area and axilla. As the fluid secreted by apocrine glands breaks down, body odor results. These glands become functional at puberty.