Skin cancer is the most common cancer in the U.S., and ways to prevent it are plentiful. New methods like UV-sensing stickers have been trending, and for good reason. They help you know when to reapply sunscreen, which is one of the best methods to protect your skin from harmful rays. Put one of the stickers on an exposed area of skin and apply sunscreen like normal, including over the sticker. As the sunscreen breaks down, the sticker will change colors, indicating it’s time to reapply. The top layer of the sticker mimics how the skin would absorb sunscreen. They start off clear or white, then turn darker as they’re exposed to UV light. Learn more about UV-sensing stickers.