In Hindu mythology Durga is Shakti, the divine feminine energy. According to a legend, Lord Brahma granted a boon to Mahishasur, the buffalo demon. Armed with infinite power, the asura created havoc in the universe, and no one could dare defeat or kill him. One fine day he ventured to Heaven or Swargaloka to kill Indra who entreated Lord Shiva for help. Enraged at such blatant misuse of Brahma’s boon, Lord Shiva along with Lord Vishnu and Lord Brahma, released their energies. The shaktis of the Trinity flashed forth and fused together, bringing to life a magnificent Goddess resplendent with many arms.
Acclaimed as Durga, she was ravishingly beautiful and deadly. The armed Durga rode a Lion and fought a fiercely bloody battle with Mahishasur, raging for nine days and nights.Finally on the tenth day, Durga trampled him under her foot and Mahishasur was killed, saving the universe from his reign of terror. The Goddess’s triumph because of her innate divinity symbolizes the victory of good over evil. These nine days are solely devoted to propitiation of the Mother Goddess or Shakti Incarnate.
Durga, the Mother Goddess of the Hindus is an amalgam of Devi (consort of a God) and Shakti (the energy of a deity personified as his wife). Believed to have manifested in various forms, the Navadurga are said to be the most sacred aspects of Durga.
Maha Kali, Maha Laxmi and Maha Saraswati
According to Hindu tradition, Durga incarnated herself in three major forms of Mahasaraswati, Mahalakshmi and Mahakali who owe their origin to Brahma, Vishnu and Shiva respectively. These three further appeared in three more forms of Durga each and thus the nine forms of Durga collectively called the Navadurga or Nine Durgas evolved.
Navratri's each night is dedicated to one form of Goddess Durga who creates, sustains and destroys the Universe. Mahakali Goddess of valor, power and energy is propitiated for the first three days to end our vices.
Shailputri is the daughter of Himalaya, king of the Mountains. Shail means mountain and putri stands for daughter. She is the first among the nine Durgas married to Lord Shiva and mother of Ganesha, the remover of obstacles and Kartikeya, god of war. The first navratra is devoted to the worship of Shailputri. Her two hands hold a trident and a lotus. Her mount is a bull.
In her previous birth she was Sati, the wife of Lord Shiva and daughter of Daksha and Bhavani. Once Daksha had organized a grand Yagna and did not invite Shiva. Being obstinate Sati however reached there and consequently Daksha insulted Shiva. Sati could not tolerate her husband being slighted and burnt herself in the fire of the Yagna.
In the next birth she was born as Parvati, daughter of Himalaya and married to Shiva. As per the Upanishadas she had shattered the egotism of Indra and other deities. Ashamed soon after, they made obeisance to her, "In fact, thou are Shakti.Whereas all of us - Brahma, Vishnu and Shiv are empowered by drawing shakti or power from you."