It is the single best thing you can do for your skin. Look for broad spectrum UV protection to protect from UVB 'burning rays' and UVA 'aging rays'. Chemical filters penetrate your skin where they absorb sun rays, so allow for approximately 20 minutes before sun exposure. Physical sun screen sits on the skin and reflects the rays. Zinc oxide and titanium dioxide are the ingredients to look for. No worries, these days physical sunscreens go on fabulously sheer. Remember, UVA rays penetrate glass, so whether you are inside or outside, rain or shine, SPF is the way to go.