The most powerful of all the divine forms of Navratri is Goddess Durga, also known as Devi and Shakti in Hindu texts. Hindu mythology says that the Goddess was the manifestation of the powers of Brahma (The Creator), Vishnu (The Preserver), Shiva (The Destroyer) and other Gods for laying down the buffalo demon Mahisasura (who had got a boon from Lord Brahma for not being killed by any man).
Goddess Durga & Mahisasura Vadh:
Mahisasura, son of Asura(demon) king Rambha and Princess Mahishi (a princess who was cursed to be a water buffalo) had a unique will power of changing himself as a human as well as a buffalo. The name Mahisasura is derived from the Sanskrit word Mahisha, which means buffalo. Upon receiving the boon from God, due to his heavy penance, Mahisasura unleashed a reign of terror on Earth. Gradually he banished Gods from heaven.
Being tortured and tormented by Mahisasura, Gods went to Brahma, Vishnu & Shiva. After listening to the distressed and woeful tales of the Gods, the Trideva decided to bring out an Adishakti (powerful divine) by combining the powers of all. This manifestation of all divine powers was given to the form of a woman. All Gods gave her their weapons to kill the demon king Mahisasura.
Goddess Durga and Her Puja:
Durga Puja (or Dussehra or Dashain, as it is called in some parts of the country) is one of the biggest annual festivals in West Bengal, Odisha, Assam, Jharkhand, and Nepal. Celebrated for over a span of 09 days (Navratri) this is one of the biggest Indian festivals which is celebrated with great pride, dedication and enthusiasm.
In Navratri, nine divine forms of the Goddess are worshipped. For the consecutive nine days different forms of the Goddess like Shailaputri, Brahmacharini, Chandraghanta, Kushmanda, Skanda Mata, Katyayani, Kaal Ratri, Maha Gauri and Siddhidatri.
The tenth day of the puja is considered to be the day of victory as on this day the Goddess is considered to have killed the demon king. It is called Vijoyadasami in West Bengal and Odisha.
Worship Goddess Durga:
Chanting the given mantras with utmost respect and sincerity can get you happiness, prosperity, good luck and will bestow you with all the divinely blessings:
Sharanye trayambake Gauri
Ya devi sarva bhutesu, shakti rupena sansthita
Ya devi sarva bhutesu, matra rupena sansthita
Namastasyai, namastasyai, namastasyai, namo namaha!
Namah prakrutyai bhadraayai niyataah pranataahsma taam
Swasthai Smritha Mathi Matheeva Shubhaam Dadaasi
Daaridrya Dukha Bhaya Haarini Kaa twadanyaa
Sarwopakaara Karanaaya saaardra Chthaaha
Bhayebhya Straahinoe Devi Durgey devi namostuthey