Sunscreens help to filter out ultraviolet (UV) radiation. Ultraviolet radiation (UVR) may cause age spots, dark spots, wrinkles, sagging as well as cancer.  The Sun Protection Factor (SPF) is a measure of how much radiation a sunscreen blocks. Broad spectrum sunscreens protect from both UVA and UVB. Sunscreen is the most important skin care product that should be used every day, even in winter to prevent signs of premature ageing.