Ultraviolet (UV) rays are a type of electromagnetic radiation that is shorter in wavelength and higher in energy than visible light, but longer than X-rays. They fall between 10 nm to 400 nm in the spectrum of electromagnetic waves. UV rays can be divided into three categories: A (320-400nm), B (280-320nm) and C (100-280nm). The Earth's atmosphere filters most of the incoming solar radiation, but a significant portion of it reaches the surface as UV rays. These rays can cause damage to living organisms by causing sunburn or skin cancer in humans, and can also harm plants, animals, and aquatic life.