what is elf on a shelf story

The story of "Elf on a Shelf" is about an elf that is sent to live with a family during the Christmas season. The elf is said to be Santa's helper and is responsible for keeping an eye on children to make sure they're being good. The elf has a unique ability to teleport back to the North Pole to report on the child's behavior, but only returns to the family after the child is asleep. The elf can take the form of any object, and children are told to be careful, as the elf could be watching at any time.