A hydrating mask is a product that is used to moisturize and provide the skin with the water it needs. These masks usually contain moisturizing ingredients such as hyaluronic acid, glycerin, vitamins and plant extracts that help maintain skin moisture and improve its softness and suppleness. Using a hydrating mask is especially useful for people with dry or dehydrated skin and can help reduce dryness, inflammation, and fine lines caused by skin dehydration. Hydrating masks are usually available in sheet, cream, or gel form and can be used periodically or as needed by the skin.