Dr. Patty Agin of the Coppertone Solar Research Center

Bet you didn't know that May is Ultraviolet Awareness and Skin Cancer Prevention Month. It's important to protect your skin from damaging ultraviolet rays whether you're walking, biking, fishing, gardening, swimming, picnicking, taking in a ballgame or just driving on a sunny day with the windows down or even up. Understanding the following suncare terms will help you decide which products are best for you.

1. Incidental Sun Exposure

The kind of exposure received unintentionally during everyday activities. For the average person, incidental time spent in the sun can account for up to 80 percent of lifetime exposure. Dermatologists rarely recommend tanning lotions -- they cite the need to protect the skin with clothing or a high-SPF sunscreen (SPF 15 or above) on a daily basis.

2. SPF

Sun Protection Factor is a comparative ratio of the ultraviolet dose required to produce minimal redness in sunscreen-protected skin, as compared with unprotected skin. The number indicates how many times longer a person can stay in the sun before beginning to burn while wearing sun protection, as compared with not wearing sunscreen. But the number is deceptive: sunscreen-induced protectiveness varies among individuals based on skin tone and genetics. SPF numbers usually range from 2 to 50. SPF 2 provides minimal coverage. SPF 50 is coverage to the max.

3. UVA, UVB, UVC

You figured out the "UV" part. It means ultraviolet radiation -- light registering beyond violet in the light spectrum and corresponding to wavelengths shorter than 4,000 angstrom units.

UVA rays are relatively constant and year round, penetrating deep into the skin's layers. UVA rays are harmful and contribute to burning, premature aging of the skin and the development of certain forms of skin cancer. UVB rays are more intense in summer months, at higher altitudes and in areas closer to the equator. UVB rays are the primary cause of sunburning, premature aging of the skin and the development of skin cancer. UVC rays are blocked by the ozone layer and do not reach the earth's surface.

4. Broad-Spectrum Protection

Refers to sunscreen products that contain ingredients to protect against both UVA and UVB rays. Some broad-spectrum sunscreens contain avobenzone, which provides extra UVA protection.

5. Photostability

It's the ability of a sunscreen ingredient to maintain its protective power and not break down during exposure to UV rays. Sunscreens with photostabilized avobenzone provide sustained UVA protection that remains highly potent during UV exposure -- some provide up to 4 hours of UV protection in laboratory settings.