The skin is your body's largest organ. It protects you against bacteria, viruses, dirt, wind, heat and cold. And it serves as a "window" to the body, alerting doctors when something is wrong.

Just when you thought you had your summertime outdoors routine down -- plenty of sunscreen, a large hat, limited exposure between 10 a.m. to 2 p.m. -- comes the news that Americans aren't getting enough of the "sunshine vitamin" -- vitamin D.

Did you know that fingernails grow faster than toenails? Or, that nails grow faster in the summer than in the winter?

It's alarming to see them, twisted and bulging, on your legs or feet, but varicose veins usually aren't dangerous.

Melatonin is a hormone that regulates your circadian rhythm, or the 24-hour cycle of biological processes called your "internal body clock."

Hives occur when something prompts cells to release histamine, a chemical found in the skin.

Are you going bald? Which conditioner should you use? Here are the answers to these and other questions about your head of hair.

Some hair on your head falls out every day, no matter what your age. And that's perfectly normal.