Today is the first Sunday of Christmas, ie within the 12 days to Christmas, which mark the period of time between the birth of Christ and the coming of the three wise men on January 6.. So there is always one Sunday of Christmas and in some years there are two. And that means that we are still celebrating Christmas, and we will continue to do so until Epiphany!

The original twelve days of Christmas were a series of religious feast days celebrated as part of the Roman Catholic Calendar in medieval and Tudor England. These were days of religious celebrations, feasting and entertainments, lasting until 6 January, and included the following (some of which the Anglican church still celebrates):

26 December, St Stephen
27 December, St. John, Apostle and Evangelist
28 December, The Holy Innocents
29 December, Memorial of St. Thomas Becket, Bishop & Martyr
30 December, Feast of the Holy Family of Jesus, Mary & Joseph
31 December, Pope St. Sylvester
1 January, Circumcision of Christ
2 January, Ss. Basil the Great and Gregory of Nazianzus
3 January, Memorial of the Holy Name of Jesus

In much of the Roman Catholic Church, Christmastide lasts longer, running through the Feast of the Baptism of the Lord on the Sunday after Epiphany.

And a 12 Days of Christmas maths test: After the 12 days of Christmas are over, how many presents has my true love sent me altogether? See the solution here: https://www.mathsisfun.com/puzzles/12-days-of-christmas.html