UV radiation is produced naturally by the sun and is also used in a variety of artificial sources, including black lights, germicidal lamps, and UV lasers. It is divided into three categories based on its wavelength: UVA, UVB, and UVC.

UVA radiation has the longest wavelength of the three and is responsible for tanning and premature aging of the skin. It can penetrate through glass and is present in sunlight all day, even on cloudy days.

UVB radiation has a shorter wavelength than UVA and is responsible for sunburn and skin cancer. It is most intense during the middle of the day and is blocked by glass.

UVC radiation has the shortest wavelength of the three and is the most dangerous to living organisms. It is mostly absorbed by the Earth's atmosphere and does not reach the surface of the Earth.

Exposure to UV radiation can have both positive and negative effects on living organisms. For example, it can help the body produce vitamin D, which is essential for healthy bones. However, overexposure to UV radiation can cause skin damage, eye damage, and even skin cancer.

To protect against UV radiation, it is recommended to wear protective clothing, use sunscreen, and limit time spent in the sun during peak UV hours.