Christmas or Christmas Day (Old English: Crīstesmæsse, literally "Christ's mass") is an annual commemoration of the birth of Jesus Christ, celebrated generally on December 25 as a religious and cultural holiday by billions of people around the world. A feast central to the Christian liturgical year, it closes the Advent season and initiates the twelve days of Christmastide.Christmas is a civil holiday in many of the world's nations, is celebrated by an increasing number of non-Christians, and is an integral part of the Christmas and holiday season.