Vijayadashami is celebrated as victory of Lord Rama over Demon Ravana and also triumph of Goddess Durga over the buffalo Demon Mahishasura. Vijayadashami is also known as Dussehra or Dasara. In Nepal Dasara is celebrated as Dashain.
Shami Puja, Aparajita Puja (अपराजिता पूजा) and Seema Avalanghan (सीमा अवलंघन or सीमोल्लंघन) are some of the rituals which are followed on the day of Vijayadashami. According to Hindu division of the day, these rituals should be done during Aparahna time.