An effective facial moisturizer contains at least one of three types of ingredients, humectants, emollients and occlusive agents, as stated by Chemist's Corner. These products are usually placed in a moisturizer in differing combinations in an attempt to maximize their benefits.
Moisturizers help improve the condition of the skin using various water-attracting and skin-barrier type ingredients. Humectants, such as glycerin, help draw water up from the lower skin layers to moisturize dry top layers. Emollients, like lanolin, help smooth out dry skin and may help skin repair itself. Occlusive agents, like petroleum jelly, preserve moisture by acting as a barrier to prevent evaporation.