In Serbian Christmas tradition, the oak log or branch burned on Christmas Eve is called the badnjak.
Traditionally, a household selects and ceremonially cuts a young, straight, undamaged oak on Christmas Eve morning. The log is then brought home and placed on the fire that evening. In cities, where a full hearth is uncommon, the badnjak is often represented by a bundle of oak twigs with their brown leaves still attached.
The burning is surrounded by prayers and wishes for health, happiness, prosperity, abundant crops, and family well-being. The custom has been interpreted as connected with the renewal of sunlight and with older beliefs about the domestic hearth and ancestors. Regional practices vary: some families prepare several logs, while others use different tree species where oak is unavailable.
Badnjak is not the same as polaznik, the first visitor associated with Christmas Day rituals, or česnica, a festive bread. Public badnjak ceremonies organized by Serbian Orthodox communities became especially prominent again from the early 1990s.