The Elf on the Shelf is a popular toy and holiday tradition in which an elf doll is used to keep track of children's behavior during the Christmas season. While the elf itself is not real, the concept is based on the idea of magical elves who report back to Santa Claus about which children have been naughty or nice. So while you won't see real elves on the shelf, it's a fun and festive way to spread some holiday cheer and encourage good behavior in children.