UV light, or ultraviolet light, refers to electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. UV light is divided into three categories based on wavelength: UVA (320-400 nm), UVB (290-320 nm), and UVC (100-290 nm). UV light is commonly used in various fields such as medicine, environmental science, and technology. UV light has the ability to kill bacteria, viruses, and other germs, making it commonly used for disinfection purposes in healthcare settings, water treatment, and sterilization of medical instruments. In addition, UV light is used in tanning beds for cosmetic purposes, in phototherapy for skin conditions such as psoriasis, and in the treatment of seasonal affective disorder. However, UV light exposure can also have negative effects on human health, including sunburn, premature skin aging, and an increased risk of skin cancer. As a result, it is important to use protective measures such as sunscreen and sunglasses when exposed to UV radiation. Ongoing research is also exploring the potential benefits and risks of UV light therapy in various medical conditions.