The official end of Feasts in the Orthodox Church

In our modern world holidays are typically 'one and done'...all celebrations are done on that day and basically forgotten the next  (Nativity being an exception with parties and other events held before and after December 25).  But, this is not the case in the Orthodox Church.  Major Feasts have a 'Forefeast' which heralds the arrival of the upcoming special day, Afterfeast days wherein parts of the services reflect the Feast which just took place  (primarily but not always exclusively in the tropria and kontakia), and finally the Leavetaking which   brings the period to an end by repeating most of the Feast's service parts.

This year the Leavetaking of the Theophany is on Sunday, January 14.  So, pay special attention for these  Theophany hymns during the service.  And keep in mind that Feastdays are the beginning, not the end, of the celebration.

Here is a Wikipedia article featuring more information and an informative chart.