The most basic function of a moisturizer is to hydrate and soften the skin. “Essentially, moisturizers assist in preventing water loss through the outer layers of skin,” Dr. Charles explains. “They can also complement the naturally found protective oils and other building blocks within the skin, such as ceramides.” This is one product that doctors recommend using year-round, for all skin types. “Skin naturally loses the ability to retain moisture as we age,” Dr. Nazarian insists, “and daily activities, such as washing, can strip natural hydrators from the surface.”