Ultraviolet (UV) radiation is a type of electromagnetic radiation with wavelengths ranging from about 100 to 400 nanometers, which is shorter than visible light but longer than X-rays

. It is produced naturally by the sun and artificially by sources such as tanning beds, mercury-vapor lamps, and electric arcs

. UV radiation is subdivided into three main types based on wavelength:

• UVA (315–400 nm): Causes skin tanning and is the least energetic but penetrates the skin deeply

• UVB (280–315 nm): Causes sunburn and can damage DNA, increasing the risk of skin cancer

• UVC (100–280 nm): The most energetic and harmful type, mostly absorbed by the Earth's atmosphere; it can cause DNA damage and is used for sterilization

UV radiation is invisible to the human eye but can be seen by some insects

. It plays a significant role in health and environmental effects, being the primary cause of skin cancers such as melanoma, basal cell carcinoma, and squamous cell carcinoma

. The amount of UV radiation reaching the Earth's surface depends on factors like time of day, season, latitude, altitude, cloud cover, and surface reflection

. In summary, UV is a form of high-energy light radiation from the sun and artificial sources, divided into UVA, UVB, and UVC, with varying effects on living organisms and important applications in disinfection and industry