So you want to get smart about being in the sun. But the choice among sunscreens is daunting to say the least. Where do you start? What do you look for? And what's octyl methoxycinnamate anyway?

Sunscreen products, unlike their sunblock cousins (we'll get to them later) absorb ultraviolet B (UVB) rays and limited amounts of ultraviolet A (UVA) rays before they can penetrate and damage your skin.

Part of the ultraviolet spectrum, UVB is a short-wave ray that reddens the skin and causes tanning. Conversely, UVA rays are the long-wave culprits that deeply penetrate the skin, damage connective tissue, and are chiefly responsible for the wrinkly, leathery "Marlboro Man" look.

UVA and UVB rays are a volatile, sunburn-inducing combination. Dermatologists surmise that if you spent your past summer vacations hanging out on the beach slathered in nothing but baby oil, all of that "tanning" has probably harmed your skin and heightened your risk of skin cancer.

 Let's first define terms.
 

The sun protection factor (SPF), listed on bottles and tubes, indicates the length of defense you'll have before harmful UVB rays start to burn your skin. What this means: If you use an SPF 15 formula, it will take 15 times as long for UVB rays to penetrate your skin than if you were bare to the sun's rays. For example, an SPF 20 formula stretches your defense to 20 times as long.
 

Water-resistant formulas keep their SPF measure for 40 minutes of "water activity" while waterproof formulas maintain their SPF for 80 minutes of "water activity." Because rating tests are staged in chlorinated pools, and chlorine water is deemed more potent than salt water, waterproof products are also considered sweatproof.
 

Some products include additives, like vitamins C and E, which purport to prevent sun damage. But the jury is still out on any added benefits.
 
 

The ABC's of How They Work

Sunblocks such as zinc oxide and titanium dioxide are the only products that offer full protection from both UVA and UVB rays. They do this by reflecting light rays. The downside is that they are pretty messy, which is not ideal if you're hanging out at a sandy beach. And unlike easy-to-apply and transparent sunscreens, sunblocks are mostly opaque shades like chalk white and neon purple. Athletes often wear bands of them on their noses and under their eyes. And you'll also sometimes see lifeguards with strips of white on their lips and smudges on their shoulders.

What Should You Get?

If you have fair skin and light-colored eyes or a family history of melanoma, you might need a higher SPF than someone with olive skin or dark eyes. Some illnesses, like lupus, increase sun sensitivity and warrant a high-numbered SPF while some allergies or concurrent drug use (i.e., antihistamines, antibiotics) could limit a sunscreen's effectiveness or aggravate an allergic reaction.
 

If you have acne or other skin problems, you might find that a lighter, gel-based product is less irritating to your skin. And if you're a hairy guy or gal, you might find that spray-on formulas are more comfortable than oil-based applications.
 
 

The choices are nearly endless. So, your first step toward good skin care is to look for a sunscreen that fits your lifestyle and personal needs and then make sure you use it!