Christmas is a holiday commemorating of the birth of Jesus Christ, celebrated on December 25th. According to the Bible, Jesus was born to Mary, assisted by her husband Joseph, in a stable surrounded by farm animals in the city of Bethlehem. Mary wrapped him in swaddling clothes and laid him in a manger (a feeding trough) because there was no room for them at the inn. The word "Christmas" originates from the term "Christ's Mass". Some people use the abbreviation "Xmas", which is an based on the initial letter chi (Χ) in the Greek word for Christ: Khrīstos (Χριστός).

The December 25th date is actually just an estimate of when Jesus was born, the Bible does not give an exact date. It is believed the date for Christmas was chosen in the 4th century by the Church due to the popularity of various ancient winter festivals around that time (less agricultural work needs to be done during the winter so people had more free time), in the hopes of replacing those festivals and encouraging the spread of Christianity through celebration.

The first Christmas celebrations were just a simple mass, but over time Christmas grew in popularity overtaking many of the other cultural holidays throughout the world. Many modern Christmas customs were influenced by the winter festivals it replaced, with traditions such as gift giving, greenery, lights, charity, merrymaking, various foods, and Yule logs ("Yule" was the name of a Scandinavian winter festival). The first commercial Christmas card was produced by Sir Henry Cole in London in 1843.

The name Santa Claus comes from the Dutch "Sinterklaas", which means Saint Nicholas. Nicholas was Bishop of Myra, in modern-day Turkey, during the 4th century. He was noted for his saintly attributes, such as the care of children, his generosity, and the giving of gifts. His feast on December 6 came to be celebrated in many countries with the giving of gifts. He traditionally appeared in bishop's attire, accompanied by helpers, inquiring about the behavior of children during the past year before deciding whether they deserved a gift or not. At the Reformation in 16th–17th century Europe, many Protestants changed the name of gift bringer to the Christ Child or Christkindl, which was Americanized to Kris Kringle, and the date of giving gifts changed from December 6 to Christmas Eve.

Because very few people have actually seen Santa Claus in person, we can only speculate about what he looks like. The modern day image of Santa Claus was created in New York after the American Revolutionary War (1775–1783). Some of the city's residents sought out symbols of the city's non-English past. New York had originally been established as the Dutch colonial town of New Amsterdam, so the Dutch Sinterklaas gift giver became known as Saint Nicholas. By the 1880s, the public depiction of Santa had evolved into the robed, fur clad, form we now recognize, possibly based on the English figure of Father Christmas.

Christmas carols started as Christmas hymns back in fourth century Rome. By the twelfth century, Chistmas carols evolved into songs. Several centuries later "wassailers" would go from house to house singing them. During the middle ages Christmas caroling was popular, but was dance focused, with a lead singer and a ring of dancers that provided the chorus. The tradition of singing carols in church did not start until the late 1800s.

In the 1800s, Christmas trees became popular and so did the tradition of exchanging gifts, which is associated with St. Nicholas, and the gifts of gold, frankincense, and myrrh which were given to the baby Jesus by the Magi. The poem "A Visit From St. Nicholas" (more commonly known as 'Twas the Night Before Christmas), written by Clement Clarke Moore in 1822, led to the widespread adoption of gift giving.

A little known fact about Christmas is that from 1647-1660, England's Puritan rulers passed a law that made Christmas illegal (although pro-Christmas rioting broke out in protest). And, in Colonial America, the Puritans of New England outlawed Christmas in Boston from 1659 to 1681. Scotland also abolished the observance of Christmas, from 1640 until 1958 when it became a Scottish public holiday again.

By the 1700s and early 1800s, the observance of Christmas had dwindled. A major turning point occured in 1843, when Charles Dickens wrote the novel "A Christmas Carol". This helped revive the spirit of Christmas due to the large popularity of the book, which portrayed the holiday as a time of family, goodwill, and compassion. Dickens took Christmas away from the community/church based celebration and made it into a family-centered festival of generosity (family gatherings, seasonal food and drink, dancing, games, and a festive generosity of spirit).

Then, in what most historians agree was the most significant Christmas related development in the past 150 years, a website named Santabot.com was launched in 2004 to allow people to chat live with Santa Claus over the Internet. The press praised it as a brilliant blend of technology and tradition, calling it "a giant leap forward in holiday revelry". Each year since, millions of children and adults worldwide have helped make chatting with Santa into a 21st century Christmas tradition.