Final answer:
Humectants are products that increase the skin's water content by drawing moisture from the air or the dermis into the epidermis, and they are a key ingredient in moisturizers along with occlusives.
Step-by-step explanation:
Products used to increase the water content of the skin's surface are humectants. Moisturizers often contain these substances because they modify the rate of water loss by absorbing water. Humectants can draw this water from the air in high humidity conditions or more commonly, from the dermis into the epidermis. They are essential components in moisturizing creams and work best when combined with occlusives, which form a coating on the surface of the skin to keep moisture from escaping. Occlusives, water, oil, emulsifier, and thickening agents are the main ingredients of creams and lotions specifically designed to protect, moisturize, lubricate the skin, and sometimes to alleviate itchiness and inflammation.