I had thought for many years that the Twelve Days of Christmas consisted of twelve days that led up to Christmas Day, but I was quite wrong!
Let me first post a link:
http://en.wikipedia.org/wiki/Twelve_Days_of_Christmas
Next, I will copy the first paragraph:
The Twelve Days of Christmas are the festive days beginning Christmas Day (25 December). This period is also known as Christmastide and Twelvetide. The Twelfth Night of Christmas is always on the evening of 5 January, but the Twelfth Day can either precede or follow the Twelfth Night according to which Christian tradition is followed. Twelfth Night is followed by the Feast of the Epiphany on 6 January. In some traditions, the first day of Epiphany (6 January) and the twelfth day of Christmas overlap.
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