At Christmas time, adoptable pixie-elves take up residence in millions of homes around the globe. The red-clad creatures are Santa's eyes and ears and a holiday hit from TV to social media.
"It's not difficult or expensive and it lasts for a lifetime," said Carol Aebersold, co-author of "Elf on the Shelf."
The book stems from the elf on the shelf tradition. Leading up to Christmas, a child's adopted elf flies back to the North Pole at night to report to Santa and returns to a new spot each morning to keep a watchful eye. It's become a hide and seek game for children and even parents. And, if you practice it in your home, Carol Aebersold, often mistaken for Mrs. Claus, is to thank.
"It started with Fisbee, my elf, when I was a child," recalled Carol.
Yes, the elf showed up every Christmas in Carol Aebersold's childhood home in Oak Ridge, Tennessee.
"It was kind of a mysterious little place to be from. Everybody worked in the plants. Nobody ever knew what their father did and you didn't dare ask."
The tradition stayed with Carol from high school to college at the University of Tennessee Knoxville and even into marriage with her husband, Bob.
"Of course, you adopt your elf for life," she explained.
She introduced her children to Fisbee when they were babies.
"By the time they were two, they were really into it. And by elementary school they were hard and fast believers."
And, of course, when they grew up, her children shared the elf tradition with their children.
Surprisingly, the idea for "Elf on the Shelf" surfaced during a very low point.
"I got hit hard with empty nest syndrome and it was a really tough time."
Her oldest twin, Chanda Bell, was encouraging her to write a book and just happened to see Fisbee sitting on the shelf.
"And she had her ah-ha moment and said, 'Mom, we should write a book about our elf tradition and tell everybody how much fun it is.' And I said, 'Chanda, I don't think anybody… oh, ok!!'"
Carol knew it was a God thing because she had the first line immediately.
"Have you ever wondered if Santa could know if you're naughty or nice each year as you grow? For 100s of years it's been a big secret. It now can be shared if you promise to keep it."
The two put their brains and backgrounds- music and English- together and crafted "Elf on the Shelf." But they couldn't find anyone to publish it.
"It was almost an impossible goal, but we all are blessed with drive."
They enlisted Chandra's twin, Christa Pitts, and began the self publishing journey, maxing out credit cards and 401Ks.
"And, we all said we're going to sink or swim together."
In 2005, the three set up shop and started their company CCA and B, LLC.
"We had one desk, one computer, one phone and whenever the phone would ring we would assume new names, so it would seem like we had a lot of people working there."
To date, they have around 70 employees and have sold more than 6 million copies of "Elf on the Shelf."
"We are the creators, the designers, the distributors."
They've also produced spin off products from the animated movie "An Elf's Story" and plush toys to a brand new birthday book complete with a cupcake costume.
"But he only gets to wear the costume for 24 hours because there is work to be done."
They didn't fully realize the staying power of their adoptable elves until they watched a helium filled version fly over the Macy's Thanksgiving Day Parade.
"That was an indescribable thrill!"
And, so are the countless letters of appreciation.
"We have some really heartwarming stories. We've had some that made us cry. We've had some that made us just roll with laughter. It's been a wonderful thing and I believe people are looking for family moments."
Which is the sole mission of this family affair- helping other families create moments together one child and one elf at a time.
Carol Aebersold and her "Elf on the Shelf", HomeGrown in Tennessee.
"Make this tradition your own."