The next time you think of going out in the sun unprotected, consider this: the sun gives off three types of harmful ultraviolet rays, each of which can penetrate deep into the skin, gradually destroying its elasticity, causing premature aging, and contributing to skin cancer. Skin cancer is serious. It accounts for more than half of all cancersin fact, one in five Americans will get skin cancer during their lifetime. To protect yourself from skin cancer you should routinely use a sunscreen product that has a sun protection factor, or S.P.F. of at least 15. People of all ages and skin types are susceptible to skin cancer, no matter how dark their skin appears. And according to the Skin Cancer Foundation, using a tanning booth may be more risky than tanning in the sun. Little is known about its long-term effects, but it is known that the exposure you get from tanning booths can cause acute sunburn, eye damage, skin cancer, and premature aging. For more information on skin cancer, consult a healthcare professional.