In Hinduism, Durga is a form of Devi, the supreme goddess, also identified with Parvati. As a Mother Goddess, she is frequently called Maa Durga and is sometimes referred to as the mother of Ganesh, Lakshmi, and Saraswati, though in some traditions she is considered the incarnation of Saraswati and/or Lakshmi.
According to the narrative from the Devi Mahatmya of the Markandeya Purana, the form of Durga was created as a warrior goddess to fight the demon Mahishasura. Through intense prayers to Brahma, Mahishasura had the boon that he could not be defeated by any man or god. By virtue of this power, he invaded the gods, who went for help to the supreme trinity (Brahma, Vishnu, and Shiva), but Mahishashur defeated all of the gods including the trinity themselves. He unleashed a reign of terror on earth, heaven and the nether worlds. Eventually, since only a woman could kill him, the trinity bestowed a dazzling beam of energy upon Uma/Parvati, the wife of Shiva, transforming her into the goddess, Durga. She was extremely beautiful, with a face sculpted by Shiva, torso by Indra, breasts by Chandra (the moon), teeth by Brahma, bottom by the Earth, thighs and knees by Varuna (the wind), and her three eyes by Agni (the fire). Each god also gave her their own most powerful weapons, Shiva's trident, Vishnu's discus, Indra's thunderbolt, etc. Later, the goddess Kali would leap out of her forehead and finally defeat Mahishasura.
The word Shakti, meaning strength, reflects the warrior aspect of the goddess, embodying a traditional male role. But she is also strikingly beautiful, and initially Mahishasur tries to marry her. Other incarnations include Annapurna and Karunamayi (karuna stands for kindness).
Blindingly beautiful, Durga is depicted as a warrior woman riding a lion or a tiger with multiple hands carrying weapons and assuming mudras, or symbolic hand gestures. This form of the Goddess is the embodiment of feminine and creative energy (Shakti).
Mahishasur's story is also of interest. His father Rambha, king of the demons, once fell in love with a water buffalo, and Mahishasur was born out of this union. He is therefore able to change between human and buffalo form at will (mahisha means "buffalo"). After conquering the three worlds, he is challenged by Durga. After several days of battle during which his army is decimated, he is finally killed on the tenth day of the waxing moon fortnight.