Feeling the sun's warm rays on your skin can be quite pleasurable-and unavoidable. Even on a cloudy day, harmful UV-A and UV-B rays can damage the skin. Because the sun is the single most cause of skin ageing, it is critical to take proper precautions when exposed to these damaging rays. Using products formulated for your skin type with an appropriate UV-A and UV-B protection factor can help prevent premature ageing caused by the sun.