Roman Saturnalia

Saturnalia was an ancient Roman festival in honor of the deity Saturn, held on December 17 of the Julian calendar and later expanded with festivities through December 23. The holiday was celebrated with a sacrifice at the Temple of Saturn, in the Roman Forum, and a public banquet, followed by private gift-giving, continual partying, and a carnival atmosphere that overturned Roman social norms: gambling was permitted, and masters provided table service for their slaves. The poet Catullus called it "the best of days."

Christian adoption

The earliest source stating December 25 as the date of birth of Jesus was Hippolytus of Rome (170–236), written very early in the 3rd century, based on the assumption that the conception of Jesus took place at the Spring equinox which he placed on March 25, and then added nine months. There is historical evidence that by the middle of the 4th century the Christian churches of the East celebrated the birth and Baptism of Jesus on the same day, on January 6 while those in the West celebrated a Nativity feast on December 25 (perhaps influenced by the Winter solstice); and that by the last quarter of the 4th century, the calendars of both churches included both feasts. The earliest suggestions of a fast of Baptism of Jesus on January 6 during the 2nd century comes from Clement of Alexandria, but there is no further mention of such a feast until 361 when Emperor Julian attended a feast on January 6 in the year 361.

In the Christian tradition the Christmas season is a period beginning on Christmas Day (December 25). In some churches (e.g. the Anglican Communion) the season continues until the day before the Epiphany, which is celebrated either on January 6 or on the Sunday between January 2 and 8. In other churches (e.g. the Roman Catholic Church) it continues until the feast of the Baptism of the Lord, which falls on the Sunday following the Epiphany, or on the Monday following the Epiphany if the Epiphany is moved to January 7 or 8. If the Epiphany is kept on January 6, the Church of England's use of the term Christmas season corresponds to the Twelve Days of Christmas, and ends on Twelfth Night.

This short Christmas season is preceded by Advent, which begins on the fourth Sunday before Christmas Day: the majority of the secularized Christmas and holiday season falls during Advent. The Anglican Communion and some Protestant churches follow the Christmas season with an Epiphany season which lasts until Shrove Tuesday which is also known as Mardi Gras or 'Fat Tuesday'. Other European cultures have their own carnival festivities between new year and Lent.

Secularisation and commercialisation

According to Yanovski et al., in the United States the holiday season "is generally considered to begin with the day after Thanksgiving and end after New Year's Day". According to Axelrad, the season in the United States encompasses at least Christmas and New Year's Day, and also includes Saint Nicholas Day. The U.S. Fire Administration defines the "Winter Holiday Season" as the period from December 1 to January 7. According to Chen et al., in China the Christmas and holiday season "is generally considered to begin with the winter solstice and end after the Lantern Festival". Some stores and shopping malls advertise their Christmas merchandise beginning after Halloween or even in late October, alongside Halloween items. In the UK and Ireland, Christmas food generally appears on supermarket shelves as early as September or even August, while the Christmas shopping season itself starts from mid November when the high street Christmas lights are switched on.

The precise definition of feasts and festival days that are encompassed by the Christmas and holiday season has become controversial in the United States over recent decades. While in other countries the only holidays included in the "season" are Christmas Eve, Christmas Day, St. Stephen's Day/Boxing Day, New Year's Eve, New Year's Day and Epiphany, in recent times, this definition in the U.S. has begun to expand to include Yule, Hanukkah, Kwanzaa, Thanksgiving, Black Friday and Cyber Monday. The expansion of the holiday season in the U.S. to encompass Thanksgiving is believed to have begun in the 1920s, when major department stores Macy's and Gimbels launched dueling Thanksgiving Day parades to promote Christmas sales. Due to the phenomenon of Christmas creep and the informal inclusion of Thanksgiving, the Christmas and holiday season has begun to extend earlier into the year, overlapping Veterans/Remembrance/Armistice Day, Halloween and Guy Fawkes Night.

The exchange of gifts is central to the Christmas and holiday season, and the season thus also incorporates a "holiday shopping season". This comprises a peak time for the retail sector at the start of the holiday season (the "Christmas shopping season") and a period of sales at the end of the season, the "January sales".

Although once dedicated mostly to white sales and clearance sales, the January sales now comprise both winter close-out sales and sales comprising the redemption of gift cards given as presents. Young-Bean Song, director of analytics at the Atlas Institute in Seattle, states that it is a "myth that the holiday shopping season starts with Thanksgiving and ends with Christmas. January is a key part of the holiday season." stating that for the U.S. e-commerce sector January sales volumes matched December sales volumes in the 2004/2005 Christmas and holiday season.

Many people find this time particularly stressful. As a remedy, and as a return to what they perceive as the root of Christmas, some practice alternative giving.

North America

In the United States, the holiday season is a particularly important time for retail shopping, with shoppers spending more than $600 billion during the 2013 holiday season, averaging about $767 per person. During the 2014 holiday shopping season, retail sales in the United States increased to a total of over $616 billion, and in 2015, retail sales in the United States increased to a total of over $630 billion, up from 2014's $616 billion. The average US holiday shopper spent on average $805. More than half of it was spent on family shopping.

It is traditionally considered to commence on the day after American Thanksgiving, a Friday colloquially known as either Black Friday or Green Friday. This is widely reputed to be the busiest shopping day of the entire calendar year. However, in 2004 the VISA credit card organization reported that over the previous several years VISA credit card spending had in fact been 8 to 19 percent higher on the last Saturday before Christmas Day (i.e., Super Saturday) than on Black Friday. A survey conducted in 2005 by GfK NOP discovered that "Americans aren't as drawn to Black Friday as many retailers may think", with only 17% of those polled saying that they will begin holiday shopping immediately after Thanksgiving, 13% saying that they plan to finish their shopping before November 24 and 10% waiting until the very last day before performing their holiday gift shopping.

According to a survey by the Canadian Toy Association, peak sales in the toy industry occur in the Christmas and holiday season, but this peak has been occurring later and later in the season every year.

In 2005, the kick-off to the Christmas and holiday season for online shopping, the first Monday after US Thanksgiving, was named Cyber Monday. Although it was a peak, that was not the busiest on-line shopping day of that year. The busiest on-line shopping days were December 12 and 13,