The Society for Creative Anachronism is a group of people who like to pretend they are living in a different time period, usually the Middle Ages. They dress up in costumes and act like they are living in that time. They do things like fight with swords, have big feasts, and make craft projects like spinning wool or blacksmithing. They call it "creative anachronism" because they are mixing things from different times and places to create their own version of history. It's kind of like playing dress-up with your friends, but for grown-ups who really like history.