Roughly 90% of all skin cancers are a direct result of ultraviolet light exposure. So, what are the best sun protection methods? And does SPF matter? Board-certified dermatologist Laurel Naversen Geraghty, MD, talks to us about what UVA, UVB, and broad spectrum means, the ideal SPF number, and breaks down the difference between mineral and chemical sunscreen. Listen in to find out the best ways to protect your skin. Related Links:  Dr. Geraghty's posts on WebMD's Healthy Skin blog American Academy of Dermatology Skin Cancer Foundation