Your skin protects you by producing a coating (a mix of oil, lipids and dead skin cells) that forms a seal and locks out viruses, bacteria and other tiny invasive agents. This protective layer pulls double duty -- not only does it keep bad things out, it helps keep your skin's moisture in. This gives your skin a healthy look and makes it soft to the touch.

But in addition to uncontrollable factors such as wind, sunlight or dry winter air, we do plenty of things ourselves that disturb or diminish that oily layer of protection on our skin.

When we bathe too often or scrub too hard, we strip away the oils we count on for skin protection. Some medications also dry out your skin as a side effect. In most cases, dry skin itself is no reason to cease treatment for the more serious affliction, but that knowledge alone won't make you less itchy or flaky.

And just what are those flakes? As a skin cell ages, it flattens (in part by losing its nucleus) and migrates outward toward the surface of your skin. Once there, it joins other flattened skin cells in forming a suit of skin-cell armor. Normally, these cells will slough off in small clusters. Dry skin is usually the result of these clusters clumping into larger bunches, which then appear as flakes of skin.

Dry skin is a malady unto itself, and it can also be a sign of a skin condition such as atopic dermatitis (a common skin allergy) or psoriasis (dry, flaky skin caused by amped-up splitting of skin cells). Skin dryness can accompany other health problems unrelated to your skin, such as diabetes or kidney disease.

Advanced treatment for these conditions may involve oral or topical drugs, such as corticosteroids or calcineurin inhibitors, which suppress the skin's immune response in order to end inflammation. As effective as these treatments may be, however, patients run the risk (especially over time) of experiencing side effects. In order to lower the risk of side effects (or to stop them once they've started), doctors may alternate treatments with emollients. Even used alone without other treatments, emollients can go a long way toward moisturizing and softening your skin, repairing the external barrier, and helping to protect your skin -- and you -- against the elements.

So what exactly is an emollient?