Moles.
Even though most are harmless, moles can develop melanoma—the most deadly form of skin cancer. Now’s the time to really pay attention, even if you’re young, you’re still at risk; this is one of the only cancers that commonly hits women under 30. The good news? “If caught in stage one, it’s very treatable,” says Dr. Martin Weinstock, Chair of the American Cancer Society’s Skin Cancer Advisory Committee. This means that everyone needs to know what to watch for. “Melanoma can look like a mole when it starts,” Weinstock says, and the first signs of the disease are a change in that mole. Not sure about yours? It should be uniform in color and have a distinct border, be oval or round and about the size of a pencil eraser. If you notice one that’s flat, or more pinkish in color, it’s more likely to become cancerous.

By staying aware of these easy-to-spot warning signs you’ll not only get more bang for your buck at your next doctor’s appointment, but you’ll give yourself a little more peace-of-mind in between. Who knows? Your newfound awareness could save your life—or at least make you look really smart when your friend asks about that mole on her back.