
The exact definition, name, and celebratory method of the period varies from culture to culture. The majority of Christian denominations in the U.S. celebrate Christmas beginning with Advent between November 27 and December 3 and ending after the Epiphany on January 6. Eastern Orthodox churches observe the Nativity Fast from September 1 through December 24 and the holiday season lasts through January 7th. In medieval pagan cultures, the season began after All Hallow's Eve (Halloween) and lasted through the Twelfth Night. The season in the United States encompasses at very least Christmas Eve through New Year's Day (the usual period for school vacations) but is now generally considered to begin with Thanksgiving and end after New Year's Day. The U.S. Fire Administration defines the "Winter Holiday Season" as the period from December 1 to January 7. Some stores and shopping malls advertise their Christmas merchandise beginning after Halloween or even in late October, alongside Halloween items.
The precise definition of feasts and festival days that are encompassed by the Christmas and holiday season has become controversial over recent decades. Traditionally, the only holidays included in the "season" in the U.S. were Christmas Eve, Christmas Day, New Year's Eve, New Year's Day and Epiphany. In recent times, this definition has begun to expand to include Hanukkah, Kwanzaa, Thanksgiving and Black Friday. 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.
adapted from Wikipedia.com