Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25[a] 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 and it 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, is observed religiously by a majority of Christians, as well as celebrated culturally by many non-Christians, and forms an integral part of the annual holiday season.