Protecting your skin from sun damage is one of the most important things you can do for your skin. Learn more:

What Causes Sunburn and Skin Damage?
There are two kinds of ultraviolet rays that reach the earth's surface: ultraviolet A (UVA) and ultraviolet B (UVB). UVB rays cause your skin to show the signs of sunburn, but most sunscreens protect against them. These rays also are partially screened out by the ozone layer, an invisible shield that protects us from the sun. But over the years the ozone layer has become thinner, so we're getting more exposure.

UVA rays don't burn your skin, but they do contribute the most damage. They penetrate your skin more deeply and affect the cells on a molecular level. That's why it's important to look for a sunscreen that will protect you from both UVA and UVB rays. UVA damage results not only in wrinkles and sagging skin, but also can cause skin cancer. And UVA intensifies with altitude, so it's particularly important to protect yourself when skiing or mountain climbing.