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 worldwide. A feast central to the Christian liturgical year is preceded by the season of Advent or the Nativity Fast. It initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many countries. It is celebrated religiously by most Christians and culturally by many non-Christians and forms an integral part of the holiday season organized around it.
Additional information
https://en.wikipedia.org/wiki/Christmas