(HealthDay News) -- Which sunscreen is right for you?

There may be no easy answer unless you understand sunscreen lingo, the American Academy of Dermatology says.

A recent study in JAMA Dermatology found that fewer than half of people asked at a dermatology clinic understood the meaning of "broad spectrum" or "SPF."

The academy offers this primer about sunscreen lingo:

  • "Broad spectrum" sunscreen means it can protect you from the sun's UVA and UVB rays. This will help prevent skin cancer, early skin aging and sunburn.
  • Sunburn protection factor (SPF) determines how well sunscreen protects from sun damage. SPF of 15 filters 93 percent of UVB rays, while 30 SPF filters 97 percent of those rays.
  • No sunscreen is entirely waterproof, but some are water-resistant. The product is considered water resistant if it stays on wet skin for 40 to 80 minutes.
  • Sunscreen should be reapplied every 2 hours, even if your skin stays dry.
  • A chemical sunscreen absorbs the sun's rays, while a physical sunscreen protects you by deflecting the sun's rays.