The 12 days of Christmas are a traditional English Christmas carol that was first published in 1780. It is a cumulative song, which means that each verse adds something new to the previous verse. The 12 days of Christmas refer to the 12 days of Christmas in the Christian calendar, which begin on December 25th and end on January 6th. The carol has become a popular holiday song, and the lyrics have been adapted in many different ways over the years.