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..[14] Christmas Day is a public holiday in many of the world's nations,[15][16][17] is celebrated culturally by a large number of non-Christian people,[1][18][19] and is an integral part of the holiday season.