What Moisturizer Does

Moisturizing products keep your skin smooth, and they prevent water from evaporating out of your skin. 
Here are three major types of moisturizing ingredients:
*Occlusives: just like Vaseline, sit on top of the skin and prevent water from evaporating.
*Emollients: usually found in lotions that include oils and fatty acids. They fill in the tiny cracks that can develop skin cells
* Humectants: another common lotion ingredient. They attract moisture, reduce flaking, and encourage your body to produce more of its own waxy substances.
All moisturizers do at least one job from these listing, and some do all three.