The Christmas season or the festive season (also known in some countries as the holiday season or the holidays) is an annually recurring period recognized in many Western and other countries that is generally considered to run from late November to early January. It is defined as incorporating at least Christmas Day, New Year's Day, and sometimes various other holidays and festivals. It also is associated with a period of shopping which comprises a peak season for the retail sector (the "Christmas (or holiday) shopping season") and a period of sales at the end of the season (the "January sales"). Christmas window displays and Christmas tree lighting ceremonies when trees decorated with ornaments and light bulbs are illuminated are traditions in many areas.

In Western Christianity, the Christmas season is synonymous with Christmastide, which runs from December 25 (Christmas Day) to January 5 (Twelfth Night or Epiphany Eve), popularly known as the 12 Days of Christmas, or in the Catholic Church, until the Baptism of the Lord, a Christmas season which can last for more or fewer than twelve days. As the economic impact involving the anticipatory lead-up to Christmas Day grew in America and Europe into the 19th and 20th centuries, the term "Christmas season" began to also encompass the liturgical Advent season, the period observed in Western Christianity from the fourth Sunday before Christmas Day until Christmas Eve. The term "Advent calendar" continues to be widely known in Western parlance as a term referring to a countdown to Christmas Day from the beginning of December, although in retail the countdown to Christmas usually begins at the end of the summer season, and the beginning of September.

Beginning in the mid-20th century, as the Christian-associated Christmas holiday and liturgical season, in some circles, became increasingly commercialized and central to American economics and culture while religio-multicultural sensitivity rose, generic references to the season that omitted the word "Christmas" became more common in the corporate and public sphere of the United States, which has caused a semantics controversy that continues to the present. By the late 20th century, the Jewish holiday of Hanukkah and the new African American cultural holiday of Kwanzaa began to be considered in the U.S. as being part of the "holiday season", a term that as of 2013 had become equally or more prevalent than "Christmas season" in U.S. sources to refer to the end-of-the-year festive period. "Holiday season" has also spread in varying degrees to Canada; however, in the United Kingdom and Ireland, the phrase "holiday season" is not widely synonymous with the Christmas–New Year period, and is often instead associated with summer holidays.