The Nativity of our Lord, God and Saviour Jesus Christ, also called Christmas, is one of the Great Feasts of the Orthodox Church, celebrated on December 25.
In the fullness of time, our Lord Jesus Christ was born to the Holy Theotokos and Virgin Mary, thus entering into the world as a man and revealing Himself to mankind.
According to the Bible and to Holy Tradition, Jesus was born in the city of Bethlehem in a cave, surrounded by farm animals and shepherds. The baby Jesus was born into a manger from the Virgin Mary, assisted by her husband St. Joseph. The odd location of the birth was the result of the refusal of a nearby inn to accommodate the expecting couple.
Though three magi from the East are commonly depicted to have visited the event, bearing gifts of gold, frankincense, and myrrh, the Bible records the coming of an unspecified number of wise men as being a few years after Jesus' birth.
Though Jesus's birth is celebrated on December 25, most scholars agree that it is unlikely he was actually born on this date. The choice of December 25 for the Church's celebration of the Nativity is most likely to have been in order to squelch attendance at pagan solstice festivals falling on the same day.
Calculating Christmas - A differing opinion of the calculation of the date of Christmas