the elf on the shelf: a christmas tradition is a 2004 children's picture book. it was written by carol aebersold and her daughter chanda bell. the book was illustrated by coë steinwart. it tells a christmas-themed story, written in rhyme. the story explains how santa claus knows who is naughty and who is nice. it describes elves visiting children between thanksgiving and christmas eve, after which they return to the north pole until the next holiday season.