Elf on the Shelf is a fun holiday tradition where a small elf doll is placed in a child's home as a Christmas decoration, and then every day, the elf moves to a new spot and watches the child's behavior. The goal is to encourage good behavior and to make sure the child is excited about the upcoming holiday. The elf reports back to Santa each night and tells him if the child has been naughty or nice, so the child must be on their best behavior.