When is Christmas Eve?

Christmas Eve is the evening or entire day before Christmas, the festival commemorating the birth of Jesus Christ. Christmas Eve is widely recognized as a full or partial holiday in anticipation of Christmas Day, which is observed around the world. Together, both days are considered one of the most culturally significant celebrations in Christendom and Western society. Christmas celebrations in the denominations of Western Christianity have long begun on Christmas Eve, due in part to the Christian liturgical day starting at sunset, a practice inherited from Jewish tradition, and based on the story of Creation in the Book of Genesis: "And there was evening, and there was morning—the first day." Many churches still ring their church bells and hold prayers in the evening; for example, the Nordic Lutheran churches.

From Wikipedia’s article Christmas Eve, by its contributors, under CC BY-SA 4.0.