what is elf on a shelf tradition

Elf on a Shelf is a tradition where an elf is placed in a home or other location during the Christmas season. The elf is said to be sent by Santa Claus to keep an eye on the children and report back to him if they have been good or bad. The elf is usually placed on a shelf or other high spot in the home and is said to move around and get into mischief. The children are then expected to behave well in order to earn a positive report from the elf.