By Science of Beauty, we generally understand the scientific activities aimed at learning about the physiology and the biochemistry of skin. This chapter will discuss healthy skin and the factors of skin damage and of skin aging, describing topical treatments aimed at maintaining skin homeostasis and at promoting repair. This chapter will not deal with invasive treatments, reconstructive surgery, and laser peeling. Since aging is the accumulation of damage, the factors of skin aging that have been identified as of today will be listed and their mode of action will be summarized in the description of the microinflammatory theory of skin aging. Topical treatments able either to prevent damage or to remove damage after environmental aggressions will be presented. Healthy epidermis will be described and some of the factors necessary for its normal functioning will be quoted. A second goal of the Science of Beauty is to prepare products able to transiently conceal surface imperfections such as dark spots, fine lines and wrinkles, and sagging skin. Ways to prolong the duration of the cosmetic effect (the so-called Cinderella effect) will be described.