Elf on a Shelf is a popular toy and tradition during the Christmas season. The idea behind the toy is that an elf is sent from the North Pole to keep a watchful eye on children and report back to Santa. The elf is then placed in a prominent location within the home, such as a shelf or mantel, where children can interact with it. Elf on a Shelf toys are available for purchase at various retail stores or online during the holiday season.