Durga Puja festival is celebrated from the sixth to tenth day of bright lunar fortnight in the month of Ashwin. This period falls in the fortnight corresponding to the festival is called Devi Paksha. Devi Paksha is preceded by Mahalaya, the last day of the previous fortnight Pitri Paksha and it ends on Kojagori Lokkhi Puja (Lakshmi Puja) on a full moon night.
Durga Puja festival marks the victory of Goddess Durga over the evil buffalo demon Mahishasura. Thus, Durga Puja festival epitomises the victory of Good over Evil. In Bengal, Durga is worshipped as Durgotinashini, the destroyer of evil and the protector of her devotees.