You may go to great lengths on a daily basis to cleanse, moisturize and protect your skin. While this daily routine may seem like a chore at times, protecting your skin actually protects the rest of your body.

Skin is your largest organ, and it protects your internal organs from outside elements like extreme temperatures, the sun's ultraviolet rays and dangerous chemicals. This shield also helps you retain water, prevent infections and produce essential proteins and vitamins -- but to do all of this, you need a lot of skin.

The average adult has about eight pounds (3.6 kilograms), or about 22 square feet (2 square meters) of skin. It may help to put that in perspective -- a standard doorway is 21 square feet, and the average adult's skin would fill all of that space [source: National Geographic].

Not all of your skin is visible to the eye. In fact, human skin has three layers: the epidermis, the dermis and the subcutaneous fat layer, or hypodermis. Each layer serves a different purpose. The epidermis is the thin outer layer that gives skin its pigment and produces new skin cells as dead cells shed. The dermis is the middle layer, and it houses pain and touch receptors, as well as blood vessels, hair follicles, collagen and elastin. The subcutaneous layer consists of collagen and fat -- it helps absorb shock and protects your body and internal organs [source: Ohio State University Medical Center].

Your skin is a constantly evolving organ that changes throughout your lifetime. In fact, humans shed about 40,000 skin cells per minute [source: National Geographic]. Your skin renews itself about once every 35 days, which means that by the time you're 20, you've already cycled through your skin about 200 times [sources: WebMD, Arizona State University].

As you can see, there's more to your skin than meets the eye. To learn more about your skin and how to protect all 22 square feet of it, see the links on the following page.