The Elf on the Shelf is a holiday tradition that involves hiding a small elf doll in a different location each day during the month of December. The doll is usually placed in a spot where children can find it easily, and the children are encouraged to look for it every day. The elf's job is to watch the children's behavior and report back to Santa whether they have been good or bad. Many parents also like to create stories and adventures for the elf to have each day, adding an extra layer of holiday magic to the tradition.