1. It’s your body’s largest organ: an average adult’s skin spans 21 square feet, weighs 9 pounds and contains more than 11 miles of blood vessels.

2. The skin releases as much as 3 gallons of sweat a day in hot weather. The areas that don’t sweat are the nail bed, the margins of the lips, the tip of the penis and the eardrums.

3. Body odor comes from a second kind of sweat – a fatty secretion produced by the apocrine sweat glands, found mostly around the armpits, genitals and anus. The odor is caused by bacteria on the skin eating and digesting those fatty compounds.

4. Fetuses don’t develop fingerprints until three months of gestation (the period during which an embryo develops (about 266 days in humans)). Some people never develop fingerprints at all. Two rare genetic defects, known as Naegeli syndrome and dermatopathia pigmentosa reticularis, can leave carriers without any identifying ridges on their skin.

5. Globally, dead skin accounts for about a billion tons of dust in the atmosphere. Your skin sheds 50,000 cells every minute.

6. There are at least five types of receptors in the skin that respond to pain and to touch. One experiment revealed that Meissner’s corpuscles – touch receptors that are concentrated in the fingertips and palms, lips and tongue, nipples, penis and clitoris – respond to a pressure of just 20 milligrams, the weight of a fly. In blind people, the brain’s visual cortex is rewired to respond to stimuli received through touch and hearing, so they literally “see” the world by touch and sound.

7. “In the buff” became synonymous for “nude” in 17th-century England. The term derives from soldiers’ leather tunics, or “buffs,” whose light brown color apparently resembled an Anglo-Saxon backside.

8. White skin appeared just 20,000 to 50,000 years ago, as dark-skinned humans migrated to colder climes and lost much of their melanin pigment.

9. The Cleveland Public Library, Harvard Law School and Brown University all have books clad in skin stripped from executed criminals or from the poor. Hopefully, they didn’t have to reprint it: One such volume is Andreas Vesalius’s pioneering 16th-century work of anatomy, “De Humani Corporis Fabrica” (On the Fabric of the Human Body).