UV filter

a clear lens filter that is attached to the front of a camera lens to block ultraviolet light and protect the lens from scratches, dust, and other types of damage

An ultraviolet (UV) filter is a clear filter placed on a camera lens to block ultraviolet light from reaching the film or sensor. This helps prevent UV light from causing haze or a blueish cast in photos, especially in outdoor or high-altitude conditions. UV filters also offer protection for the lens, shielding it from dust, scratches, and other potential damage.