A muff is like a fluffy pillow that you can wear on your hands to keep them warm. Sometimes it's made of fur or fake fur, and sometimes it's made of other soft materials. You can stick your hands inside the muff and they'll stay nice and toasty, even when it's cold outside! It's kind of like a pocket for your hands, but instead of being in your coat, it's separate and you can carry it around with you. It's an accessory that can make your outfit look fancy and stylish while also being practical by keeping your hands warm!