Elf on the Shelf is a beloved holiday tradition that originated in Germany. The story goes that Santa needs a way to keep an eye on children's behavior throughout the year, so he sends a group of elves around the world to watch and report back. One of these elves is placed on a shelf in a home, where they observe the children's actions and report back to Santa every night. The children must be nice and behave well, otherwise the elf might move to a different location or even play a prank on them!