Christmas (Old English: Crīstesmæsse, meaning "Christ's Mass") is an annual commemoration of the birth of Jesus Christ[6][7] and a widely observed cultural holiday, celebrated generally on December 25[3][4][5] by billions of people around the world.[8][2][9] A feast central to the Christian liturgical year, it closes the Advent season and initiates the twelve days of Christmastide, which ends after the twelfth night.[10] Christmas is a civil holiday in many of the world's nations,[11][12][13] is celebrated by an increasing number of non-Christians,[1][14][15] and is an integral part of the Christmas and holiday season.