Ultraviolet (UV) radiation is a form of electromagnetic radiation with wavelengths shorter than visible light, but longer than X-rays. UV radiation is emitted by the sun and is divided into three categories based on wavelength: UVA, UVB, and UVC. UVA and UVB radiation can penetrate the Earth's atmosphere and have various effects on living organisms, including causing skin damage, increasing the risk of skin cancer, and affecting the immune system. Research in the area of UV radiation focuses on understanding its biological effects, developing protective measures, and exploring potential applications in fields such as medicine, material science, and environmental monitoring.