Skin is the part of the outer body that is most often exposed to external factors, especially ultraviolet radiation. The skin has an important role in supporting the appearance so that it can affect human social life. Skin aging is a process of decreasing the body's physiological functions that cannot be avoided. The aging process of the skin can be caused by a decrease in collagen density and replacement of essential structural proteins so that the skin loses its integrity and elasticity. Collagen is the most abundant protein in humans which can be found in bones, muscles, skin and tendons. Several studies have shown that damaged collagen fibers can be replaced by new fibers when collagen production is stimulated, which is why many cosmetic industries are competing to develop the use of collagen. Collagen has shown potential as an antioxidant, skin moisturizer, and anti-aging. Therefore, this article examines the benefits of collagen, especially in the cosmetic field. This article also discusses the sources of collagen with the best properties as active ingredients for skin care products