Children are told that Santa Claus watches them sleep and keeps a list of their every move to judge whether they are good enough to receive prizes made by the elves in his sweatshop. He then enters homes to eat cookies and leave behind toys.
The very beginning of the phenomenon known as Santa Claus of course all started with the famous Saint Nicholas, of Myra, a priest in the 4th Century. There are approximately 47230234898907 different versions of how the man became known and they're all pretty similar so here's one of them:
There was a family that lived near (not yet Saint) Nicholas that was so broke that the father decided to sell his three daughters into marriage. The eldest was to go first but Nicholas felt sympathetic for the girl and he tossed money down the family's chimney so they would not have to sell her. When the second daughter was old enough to be sold, he did the same thing. Finally, when the youngest daughter was in danger, the girls father stayed up to catch Nicholas in the act. Nicholas became a Saint and years later people began exchanging gifts on SainT Nicholas Day, December 6. This however eventually changed to the 25th to suit Jesus.
So how did he become Santa Claus? The word for 'saint' in German is 'Sinter' and a derivative of Nicholas is Klaas (apparently). Sinter Klaas became Santa Clause because it sounds cooler.
Joulupukki is the Finnish Santa, literally the name means Yule goat. The old tradition is that after Christmas, old men would dress in a goat costume and perform for leftover food. Surely nobody could resist feeding the adorable old goat men.
Somehow the Joulupukki transformed into the modern Finnish version of the American Santa (aka the real one). Only his workshop is in the Mountains of Korvatunturi. This is where the idea of Santa riding with reindeer came from, because Finland is so full of them that they sell reindeer meat in supermarkets. Joulupukki's reindeer don't fly however because he doesn't sneak in through any chimneys. He instead walks right on up to the front door while the children are asleep and when the parents of the house answer he asks them "Are there any well behaved children here?"
The idea that Santa enters through the chimney is probably because Saint Nicholas threw the money down there. The idea was popularized with the poem 'A Visit From Saint Nicholas' or 'Twas the Night Before Christmas' but in this version he was tiny. He is described as being little, lively and quick, with a miniature sleigh and eight tiny reindeer.
Now being a big fat man, the popular consensus is that he gets in through the chimney by using Christmas Magic or something.
So because there are reindeer up North, American culture swiped this idea quickly. The concept of them flying is believed to come from the Sami people of Lapland. Their reindeer ate poisonous mushrooms and their urine would serve as a hallucinogenic. Yes, when they drank it. Some of them claimed to have out of body experiences described the sensation as 'flying'. So they were deemed to be magic reindeer.
The reindeer were given names thanks to the same poem mentioned earlier and they all stuck. That guy pretty much wrote Christmas.
Rudolph came later on in a Finnish poem called 'Petteri Punakuono' meaning 'Peter Rednose'. This idea was swiped too and turned into the song 'Rudolph the Red Nosed Reindeer' which is not nearly as cool.
Santa has had many looks over time, he was originally a skinny old man in bishop robes. For many years following he didn't have one single look, he was portrayed by different people as being fat, skinny, muscular and tiny. He wore green, blue, purple and animal print even. He has on several occasions been drawn as an elf.
Cartoonist Thomas Nast began drawing Santa in red outfits and this was eventually ripped off by Coca Cola for an advertising campaign. they used the same image of Santa in advertisements for years, in coca cola, and eventually it became the accepted look.
The modern day version of Santa Claus is a combination of a saint, Finland and coke.