Ultraviolett, or ultraviolet (UV) light, is a type of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. It is divided into three categories: UVA, UVB, and UVC, each with different effects on living organisms. UV light is primarily produced by the sun and can also be generated artificially through lamps. Ultraviolet light has various applications, including sterilization, as it can kill bacteria and viruses. It is also used in fluorescent lamps and for detecting certain substances. However, excessive exposure to UV radiation can lead to skin damage and increase the risk of skin cancer.