As our skin gets older, it produces fewer lipids. Lipids are the oils in the skin that hold onto moisture and give younger skin that youthful smooth glow. We tend to address this in two ways: wear more make-up to add smoothness and highlights; and wear more or heavier moisturizer.
While there is nothing wrong with either of those things, they can lead to bigger problems. Removing make-up with harsh cleansers can strip more lipids from the skin, drying it out and even causing irritation. Moisturizers are typically made mainly from waxes and water (look for things like paraffin and stearic acid) with a few oils and nutrients added. They are effective because they form a protective layer on the skin that holds in moisture. However, this can mean that the small amount of nutritious ingredients in the moisturizer can't penetrate into the skin where they're needed. Also the waxes can build up and block pores, leading to outbreaks and blemishes, in turn making us wear more make-up or use more harsh cleansers and so the cycle continues.
Oil based facial serums help break this cycle. A high quality facial oil contains nutrient rich oils that penetrate into the skin, replenishing the lipids, and giving the skin a more youthful smooth glow. Because there is no water or wax, it means that the product is naturally microbe free and so doesn't need artificial preservatives. It also means that the product is much higher in therapeutic ingredients so you only need a small amount to get the benefits. Once the skin has been quenched by the facial oil, a light moisturizer can be used to hold in the oils and protect the skin from the sun and other elements.
This naturally nourished skin doesn't need to be covered up or enhanced with make-up, so you can simplify your beauty needs and be confident in your healthy, glowing skin.