On the 24th of December every year children around the world put out milk and cookies in the hopes of luring a magic fat man into their home who will leave presents behind before sneaking into the house next door.
How did such an odd tradition begin?
You can pretty much blame Northern Europe, where the winter weather is cold and dark and depressing.
And the coldest and darkest and depressingest day is the Solstice on December 21st or 22nd when the sun only gives a few weak hours of light if any at all.
These sun-deprived people invented magical characters to visit them and lighten the mood by bringing gifts and celebrations.
These characters ranged from elves to Gods to goats, but there are two of particular interest to the modern story.
The first is St. Nick, in the Netherlands. St. Nick is thin and perhaps a bit stern, but still brings presents to children early in December.
He dresses like a bishop in red and white with a staff and rides on a horse named Amerigo, for whom Dutch children are encouraged to leave out a carrot. St. Nick is called Sinterklaas in Dutch.
The second character is Father Christmas from England. Father Christmas is a big, jolly pagan dressed in green with a holly wreath on his head.
Traditionally he is less concerned with children and gifts than he is with food and wine and celebration and is perhaps best known for being one of the three spirits of Christmas who terrorize Scrooge.
When Europeans settled the Colonies, St. Nick and Father Christmas and the other characters began to mix together.
This explains why the US version has so many names.
Santa Claus is the Americanization of Sinterklaas, but he's also called St. Nick and Father Christmas and Kris Kringle which comes from Germany.
In the old world these were different characters, but in the new world over time they evolved into one, which you can see happening in older stories.
For example, the poem, "The Night Before Christmas" came out in 1823 in New York which established that Santa lands on the roof and fills stocking with toys.
But this Santa is an elf, much like those from the Nordic Countries.
He's small and drives a miniature sleigh with tiny reindeer—which makes a lot more sense for someone whose job description includes fitting down chimneys.
Also, the word, "Santa" appears nowhere in the poem. The original title is "A visit from St. Nick."
As the 1800s continued, a fat, human looking immortal Santa evolved into the standard among American authors.
It was in the states that he gained both his elvish workforce and a wife.
By about 1900 Santa had developed his current iconic style.
It should be noted that, contrary to popular belief, Coca-Cola didn't change his colors to their corporate scheme.
But instead used the conveniently red-and-white Santa in 1931 to help sell more soda during their off season.
Though Coke didn't create him, their omni-present ads probably did brand this as the One True Santa in the minds of millions helping spread him round the world to many cultures with no traditions of winter gift-givers.
This American Santa in-turn influenced his relations in Northern Europe to become more like him, although not always to the pleasure of the locals.
In particular, the British Father Christmas has been completely assimilated into the Santa collective to the point where many Britons don't realize they were ever separate.
In the Netherlands, however, St. Nick is still successfully holding his own as a distinct character.
The one last detail about modern Santa that's still up for debate, at least between countries, is where exactly he lives.
In the late 1800s his home was the magnetic north pole centered under the aurora borealis.
While this would be the most diplomatic option for Santa, Magnetic North has since moved off the Polar Ice Sheet and into the Ocean, a rather inconvenient place to set up a toy factory.
So Canada claims his workshop is somewhere in Nunavut and has given Santa a post code and—no joke—official Canadian citizenship.
The American response is that the North Pole doesn't refer to the obviously inhospitable sheet of non-domestic ice but rather to the little town of North Pole, Alaska.
Denmark claims he lives in their former colony of Greenland. And Greenland, not surprisingly, agrees.
The Nordic countries quarrel about his exact location, but Finland is the clear winner of this argument with his workshop in Rovaniemi on the Arctic Circle.
For the evidence inclined, you can actually go visit Santa there and see the elves, toys, reindeer and post office, which makes Finland's claim pretty strong.
Santa is even available during the off season.
But, no matter where he might be based, Santa still manages to get around the world in just one night to deliver all those presents...and eat all those cookies.