The function of the skin as a barrier protects underlying tissues from infection, desiccation, chemicals, and mechanical stress. Disruption of this function results in increased transepidermal water loss or TEWL and is associated with conditions like atopic dermatitis and other chronic skin diseases. Moisturizers have been shown to improve these conditions through restoration of the integrity of the stratum corneum, acting as a barrier to water loss and replacement of skin lipids and other compounds. Also, Moisturizers are commonly used to reduce fine lines and make skin appear smooth and soft. While many products make extensive claims of skin rejuvenation, many of the beneficial effects of these products are actually due to the Moisturizers they contain: ingredients like glycerin, petrolatum, and dimethicone. Some newer formulations like prescription-device Moisturizers, which received 510 K approval on the basis of reducing TEWL, are significantly more expensive than traditional Moisturizers and recent literature does not indicate that they are more effective than their over-the-counter counterparts.