UVA, UVB and even UVC - does it really matter to U? Actually, the different wavelengths of the sun's rays do matter when it comes to your skin. Ultraviolet radiation is the light that reaches earth from the sun. First, cross UVC rays off the list - they don't have a significant impact. UVB rays are the ones that react with melanin in your skin to tan or burn it, and that's a direct way to measure skin damage from the sun. More sunburns mean a higher risk of skin cancer. And that's where UVA rays come in. These rays have a longer wavelength and penetrate the skin more deeply, affecting areas where skin cancers are triggered. UVA rays affect skin's DNA, and skin can darken as a protective mechanism to slow damage. The sun's rays, along with a decrease in collagen production and gravity, can accelerate the aging process. UVA rays further cause collagen to deteriorate and that reduces skin elasticity. Where can you find the most damaging UVA rays?

Tanning beds. According to the Skin Cancer Foundation, "fake and bake" tanning emits up to 12 times more UVA rays than the sun. Tanning bed exposure in youth can increase melanoma risk by as much as 75 percent, and people who use tanning beds regularly are more likely to have other skin cancers, too. Keeping out of the sun, especially during the hours of 10 a.m. to 4 p.m., is the only surefire way to stay safe. Sunscreen with SPF delays the effects those UVB rays have on your skin, but the FDA hasn't established criteria for measuring protection against UVA rays. New labels do show ratings of UVA and UVB protection, so look for a sunscreen that scores high on both of these assessments to best protect your skin.