The UV ultraviolet (or actinic rays) are electromagnetic radiation of the ultraviolet band, which act at the skin level, since most of them are absorbed by the skin without reaching the deepest layers. The most important effect is the stimulation of melanin production which, in addition to promote tanning, has a protective action and bactericidal against many microorganisms. The UV rays are then particolarmete indicated in the treatment of dermatological diseases, and in particular the reduction of blemishes in the case of beauty treatments.