The skin is just not a covering layer of the body; it is more than that and functions as an active organ, performing its essential role. It also functions as a protective layer to protect from environmental damage, helps maintain body temperature, permits sensory feel and pain, and provides immune defense. In this chapter, we discussed the skin organization, including the epidermis, dermis, and hypodermis, along with its major elements such as sebaceous glands, sweat glands, and hair follicles. This chapter mainly focused on explaining how ultraviolet (UV) radiation impacts the skin. The short-term exposure to UV rays exhibits redness or sunburn, while long-term exposure to UV rays is directly linked to photoaging, reduced immune protection, and even skin cancer. The UV light provokes the generation of reactive oxygen species (ROS) that may damage the DNA and influence the key signalling pathways. The skin possesses its own system of defense, e.g., the production of melanin, and employs antioxidants, which prevent damage to the skin. All these studies demonstrate how the sunrays may alter the operation and structure of skin and long-term exposure to such UV rays raises the risk of skin complications, such as cancer.