Deciding to slather on sunscreen should be a no-brainer. The hard part is choosing one that's right for your skin type. Even if you have a deep, dark tan, you still need to use sunscreen. Experts recommend using one with an SPF of at least 15 (higher if you have fair skin or live in the South or at a high elevation.) You should apply it liberally to all exposed body parts at least 30 minutes before going out in the sun. Then make sure you reapply every two hours and after swimming or sweating.

And if you're still holding on to last year's sunscreens, don't. Some ingredients degrade, so get rid of old sunscreens and buy some new ones. To help you make sense of the ingredients and terms you'll see on the bottle, here's a guide to sunscreen lingo.

Just click on the words to get their definitions.

Avobenzone: Also known as Parsol 1789, it protects against both UVA and UVB rays.

Broad-spectrum protection: A broad-spectrum sunscreen helps protect your skin from ultraviolet A (UVA) as well as ultraviolet B (UVB) rays. UVA rays cause premature wrinkling and may cause skin cancer. UVB rays burn and are considered the main cause of basal and squamous cell carcinomas as well as a significant cause of melanoma. Experts recommend using a sunscreen that protects against both types of ultraviolet radiation.

Lotion, cream, or gel: One is not more effective than another, so the type of sunscreen you choose depends on your preference. You may want to use a cream on your face, since gels can sting around the eyes.

Oil-free: Look for this label if you have oily or acne-prone skin and want to avoid breakouts caused by sunscreen.

PABA or PABA-free: Short for para-aminobenzoic acid, and used in many sunscreens, but some people are allergic to it. If you're one of those people, make sure to look for a PABA-free sunscreen.

SPF: Short for sun protection factor, SPF measures the length of time a product protects against skin burning from ultraviolet radiation, compared to how long the skin takes to burn without protection. If it takes 20 minutes without protection to begin burning, using an SPF 15 sunscreen theoretically prevents burning 15 times longer -- about 5 hours. Experts recommend using a sunscreen with an SPF of at least 15, since that number blocks most of the sun's rays.

Ultraviolet (UV) radiation: Invisible rays that are part of the energy coming from the sun. UV radiation that reaches the earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation may also add to skin damage that can lead to skin cancer.

Waterproof: Indicates that the product provides protection for at least 80 minutes even when swimming or sweating.

Water-resistant: Different from waterproof, this means that the product provides protection for only 40 minutes while swimming or sweating.

Zinc oxide, talc or titanium dioxide: These ingredients are non-chemical, physical sunblocks. They provide good coverage, are waterproof and, most important, cause fewer allergic reactions than chemical sunscreens. The only drawback: These products are not absorbed by the skin, so they tend to create a masklike appearance.