Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A liturgical feast central to Christianity, Christmas preparation begins on the First Sunday of Advent. Advent is followed by Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many countries and is observed by a majority of Christians; it is also celebrated culturally by many non-Christians and forms an integral part of the annual holiday season.