According to the Hindus, Devi Durga is great among all the goddesses. She is the consort of Lord Shiva and worshiped in various forms corresponding to her two aspects: 'Benevolence' and 'Fierceness'. She is known as Uma, "light"; Gauri, "yellow or brilliant"; Parvati, "the mountaineer"; and Jagatmata, "the-mother-of-the-world" in her milder guise. The terrible which originates are Durga "the inaccessible"; Kali, "the black"; Chandi, "the fierce"; and Bhairavi, "the terrible."
Devi Durga, a beautiful warrior seated upon a lion wearing a beautiful red cloth saree is her first appearance of the great goddess. The circumstance of her miraculous arrival was the tyranny of the buffalo demon Mahishasur, who through terrific austerities and had acquired invincible strength after blessed with a boon from Lord Brahma.
The gods were afraid of this buffalo demon because neither Lord Vishnu nor Lord Shiva could prevail against him. It seemed that the joint energy of Shakti from the Gods was only capable of defeating Mahishasur, and so it was the eighteen-armed Devi Durga who went out to do battle against Mahishasur and she killed him.
Devi Durga went to battle on her ferocious lion 'Sinhavahini', armed with celestial weapons given to her by the other Gods with anger and aggressive aspects of the goddess Shakti, whose role in Hindu mythology was to fight and conquer the evils and also personify the female Shakti. In the battlefield, she fought and killed the evil Mahishasur and restored back heaven to the Gods. Since then the goddess is invoked for protection from the powers of evil. Durga Puja is observed in her honor, to celebrate her victory over evil everywhere in India.