The skin is composed of three layers of differentiated tissues. The most external layer is the epidermis, followed by the dermis and the hypodermis, which is the most internal layer of the skin. The increasing incidence of skin cancer has led international health authorities to recommend protection measures to prevent the harmful effects of skin exposure to UV-radiation. Such measures include avoidance of sun exposure, especially at times when disease-inducing wavelengths are more intense, wearing protective clothing and use of topical sunscreens. This book discusses the various properties of sunscreens, the role sunscreens play in skin cancer, and other health effects for individuals using sunscreens.