Christmas or Christmas Day (Old English: Crīstesmæsse, meaning "Christ's Mass") is an annual festival commemoratingthe birth of Jesus Christ, observed generally on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year, it closes the Advent season and initiates thetwelve days of Christmastide, which ends after the twelfth night. Christmas is a public holiday in many of the world's nations, is celebrated culturally by a large number of non-Christian people, and is an integral part of theChristmas and holiday season.
While the birth year of Jesus is estimated among modern historians to have been between 7 and 2 BC, the exact month and day of his birth are unknown, and are not the focus of the Church's Christmas celebration. His birth is mentioned in two of the four canonical gospels. By the early-to-mid 4th century, the Western Christian Church had placed Christmas on December 25, a date later adopted in the East, although some churches celebrate on the December 25 of the older Julian calendar, which, in the Gregorian calendar, currently corresponds to January 7, the day after the Western Christian Church celebrates the Epiphany. The Council of Tours of 567 "declared the twelve days between Christmas and Epiphany to be one unified festal cycle", thus giving significance to both December 25 and January 6. The date of Christmas may have initially been chosen to correspond with the day exactly nine months after early Christians believed Jesus to have