January 6th is Epiphany or Twelfth Night

Twelfth Night is a festival in some branches of Christianity marking the coming of the Epiphany and concluding the Twelve Days of Christmas.

It is defined by the Shorter Oxford English Dictionary as "the evening of the fifth of January, preceding Twelfth Day, the eve of the Epiphany, formerly the last day of the Christmas festivities and observed as a time of merrymaking" There is some confusion these days, however, as to which night is Twelfth Night: modern practice is often to regard the night of Epiphany itself (sixth of January) to be Twelfth Night. The older tradition of Twelfth Night being the 5 January stems from the medieval practice of the day beginning at sunset, rather than at midnight as it does now. Thus Twelfth Night falls on 5 January, ahead of Twelfth Day on the 6th.

A recent belief in some English-speaking countries holds that it is unlucky to leave Christmas decorations hanging after Twelfth Night, a belief originally attached to the festival of Candlemas which celebrates the Presentation of Jesus at the Temple (2 February).