Christmas or Christmas Day (Old English: Crīstesmæsse, meaning "Christ's Mass") is an annual festival commemorating the birth of Jesus Christ,[7][8] observed most commonly on December 25[4][9][10] as a religious and cultural celebration among billions of people around the world.[2][11][12] A feast central to the Christian liturgical year, it is prepared for by the season of Advent orNativity Fast and is prolonged by the Octave of Christmas and further by the season of Christmastide. Christmas Day is a publicholiday in many of the world's nations,[13][14][15] is celebrated culturally by a large number of non-Christian people,[1][16][17] and is an integral part of the Christmas and holiday season.

The celebratory customs associated in various countries with Christmas have a mix of pre-Christian, Christian, and secularthemes and origins.[18] Popular modern customs of the holiday include gift giving, completing an Advent calendar or Advent wreath, Christmas music and caroling, an exchange of Christmas cards, church services, a special meal, and the display of various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, andholly. In addition, several closely related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body oftraditions and lore.[19] Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity, the holiday has become a significant event and a key sales period for retailers and businesses. The economic impact of Christmas is a factor that has grown steadily over the past few centuries in many regions of the world.