1. December 25 became the official celebration date for the birth of Christ in 350 A.D. popes-and-papacy.com / Via history.com In the fourth century, church leaders wanted a day to commemorate Christ's birth. The Bible doesn't specify the date he was born, so Pope Julius I proclaimed it would be celebrated on December 25. Because celebrating Christ's birth isn't mentioned in the Bible and because December 25 coincided with pagan winter solstice festivals, some Christians disavowed the holiday. The Pilgrams didn't celebrate it, and Christmas wasn't declared a federal holiday in the U.S. until 1870. 2. Germany is credited with popularizing the tradition of the Christmas tree. sacred-texts.com / Via history.com Even before Christmas was established, trees that were green all year long were symbolic for people in the winter. German Christians began putting trees in their homes in the 16th century, and it's believed Martin Luther was the first to decorate the tree with candles. German immigrants in Pennsylvania brought the tradition to the U.S. 3. The idea of Santa Claus originated with a monk in present-day Turkey named St. Nicholas in the third century. vintageholidaycrafts.com / Via history.com St. Nicholas was said to have inherited a fortune that he gave away to the poor and sick. His legend and popularity spread through Europe with feasts commemorating him held on the anniversary of his death. His was particularly popular in Holland where he was known as "Sinter Klaas." Our modern depiction of Santa Claus was popularized in the 19th century in advertisements. 4. The first Christmas card was sent in 1843 in the U.K. s3-ak.buzzfeed.com / Via whychristmas.com Sir Henry Cole, a government worker, and John Horsley, an artist, created the first Christmas card depicting people helping the poor and enjoying Christmas dinner with their family. Early Christmas cards usually had the Nativity, snow scenes or robins on them. 5. The U.S. Postal Service has been answering children's letters to Santa for 100 years. graphicsfairy.blogspot.com / Via about.usps.com In 1912, Postmaster General Frank Hitchcock authorized the U.S. Postal Service to respond to children's letters to Santa. By the 1940s, charitable organizations, companies and other community groups were invited to help respond the growing number of letters. According to the U.S. Postal Service, children often address their letters to "Santa Claus, North Pole, Alaska," and many wish Santa a happy birthday. 6. The White House has put up an official Christmas tree since the Great Depression. nydailynews.com Although many presidential administrations set up Christmas trees in the White House, First Lady Lou Henry Hoover is credited with beginning the unbroken tradition of the official White House Christmas tree in 1929. In 1961, First Lady Jacqueline Kennedy began the tradition of selecting a theme for the Christmas tree. This year, First Lady Michelle Obama selected the theme "Joy To All." 7. Rudolph the Red-Nosed Reindeer was created as a character in a department store coloring book. etsy.com / Via news.discovery.com The Montgomery Ward department store purchased and gave away Christmas coloring books to shoppers every year. In 1939, they decided to make their own and commissioned Robert May, a copyright, to develop a story for the coloring book. He created Rudolph the Red-Nosed Reindeer. 2.4 million coloring books were distributed the first year. Ten years after Rudolph was created, Gene Autry recorded the song "Rudolph the Red-Nosed Reindeer," which was written by May's brother-in-law. 8. Bing Crosby's "White Christmas" is the best-selling song of all time. vice.com Songwriter Irving Berlin, who also wrote "God Bless America" and "There's No Business Like Show Business," wrote "White Christmas" in 1940 in a hotel in either La Quinta, California or Phoenix, Arizona depending on who you ask. The song has sold 50 million copies and has been covered more than 500 times. 9. Holiday shopping can make up to forty percent of a company's retail sales. Getty/Orlando / Via moneycrashers.com To lure shoppers, stores have relied on discounts, deals, free shipping and no-fee layaway. Historically, the Saturday before Christmas has been the biggest shopping day of the year, but since 2002, Black Friday has become the top sales day. This year, sales are down 4.3 percent from 2011, according to the Washington Post. 10. "Xmas" isn't actually taking Christ of out Christmas lifetheologydrpepper.wordpress.com The "X" comes from the Greek translation of Christ, Χριστός, and "X" has historically used by artists and writers to symbolize Christ. Still, some have seen the use of Xmas as disrespectful. The 1948 Vogue's Book of Etiquette stated "'Xmas' should never be used" in greeting cards," and today, its use is discouraged by the AP Stylebook, the New York Times, The Times, The Guardian and the BBC. 11. Candy canes were originally all white. candyblog.com / Via gpb.org The candy cane was allegedly created in Germany in the 19th century when a choirmaster wanted to create something the children could enjoy during church service. He created an all-white candy in the shape of a shepherds crook as a reminder of the shepherds who visited Christ. The red stripe wasn't added until later. Today, Bobs Candies (no apostrophe) is the largest manufacture of candy canes, and they also created the largest candy cane ever, an eight-foot-long striped cane that weighed more than 100 pounds. 12. There's this thing called a caganer and people put it in their Nativities. mytravelthirst.com No one really knows what this thing is or why it's defecating or why people put it in their Nativities, but in parts of Spain, Portugal, France and Italy, it's a thing people do sometimes. There are a lot of explanations for it, including it being a symbol that God doesn't necessarily manifest himself when people are ready or just being something that kids laugh at and think it funny.