By now, most of us have a pretty good grasp on this whole skin cancer thing. I bet you wear sunscreen, avoid sunburns, and tell your dermatologist about any weird moles. But some signs of skin cancer are difficult to spot, making it all the more important to stay informed.

So, let’s start off by talking about what, exactly, can cause the disease. “Skin cancer is the uncontrolled growth of abnormal skin cells,” dermatologist Dr. Marina Peredo, of Skinfluence in NYC, tells Bustle. “While genetics can play a role, Ultraviolet (UV) radiation from the sun is the number one cause of skin cancer.” This is true for the light from tanning beds, the blazing sun on the beach, and any sunlight exposure you get during the winter.

If you know what to watch out for, and monitor your skin monthly for changes, you can increase your chances of catching skin cancer in its earliest stages. “Skin cancers found and removed early are almost always curable, so it’s important to pay attention to your skin’s changes and flag anything that seems unusual,” Peredo says. “Additionally, the longer you wait, the deadlier it becomes. There is also a greater chance of scarring for skin cancers that have been on the skin for a long time.” Since you don’t want any part in that, read on for some subtle signs to watch out for.