Ultraviolet lamp, also called Black-light Lamp, device for producing electromagnetic radiations in the wavelengths between those of visible light and X-rays. The Sun’s rays are rich in such radiation, sometimes referred to as black light because it is not visible to the unaided eye. UV exposure is a powerful attack on the skin, creating damage that can range from premature wrinkles to dangerous skin cancer. Damage from UV exposure is cumulative and increases your skin cancer risk over time. While your body can repair some of the DNA damage in skin cells, it can't repair all of it.
Reference : Wikipedia