Sunglasses or
sun glasses are a form of
protective eyewear designed primarily to prevent bright
sunlight and
high-energy visible light from damaging or discomforting the eyes. They can sometimes also function as a visual aid, as variously termed spectacles or
glasses exist, featuring lenses that are colored,
polarized or darkened. In the early 20th century they were also known as
sun cheaters (
cheaters being an
American slang term for glasses).