Navaratri is a composite festival celebrated all over India. Depending on gauna - local tradition, but for most beginning with the New Moon (Amavasya - dark moon night) or for some on the ninth day of the month of Virgo (Kanya) just prior to the Amavasya, or on the first day of the Hindu month of Ashwina (Padmanabha - Vaishnava mase), various ceremonies are performed. T essesnce of this festival consists of fasts and worship of nine aspects of Durga, one on each of the nine days. Navaratri is known as the Festival of Nights honoring the goddesses beginning
Consequently this festival of Navaratri is popularly known as Durga Puja in Bengal. After these nine days comes the Dashami, the tenth day, which is the day of the famous festival of Dussehra or Vijaya Dashami ( the tenth day of victory ). This is the day Lord Rama had killed Ravana, signifying the victory of good over evil. Vaishnavas generally being absorbed in Vijay Dashami rather than Durga puja.
" Rishi Markyndya" has given detail about Ma Durga and its nine forms. She is a form of "Shakti and power". The evolution of Shri Maha Saraswati, Shri Maha Laxmi and Shri Mahakali (the 3 main forms of "Shakti") took place from Shri Brahma, Shri Vishnu and Shri Mahesh respectively. Each of these 3 deities gave rise to 3 more forms and hence in all, these 9 forms together are known as Nav-Durga .....
1. Shailputri-1st night devoted to the puja of Ma Shailputri. Shail means mountains; Parvati, the daughter of king of Mountains Himavan, is known as "Shailputri". Her 2 hands, display a trident and a lotus. She is mounted upon a bull.
2. Bhramcharni- One hand holds a "Kumbha" or water port and the other rosary. She personifies love and loyalty. Bhramcharni is store-house of knowledge and wisdom. Rudraksha is HER most adorned ornament.
3. Chandraghanta- Worshipped on the 3rd night this Ma Durga Shakti is astride a tiger, displays a golden hue to her skin, possesses ten hands and 3 eyes. Eight of her hands display weapons while the remaining two are respectively in the mudras of gestures of boon giving and stopping harm. Chandra + Ghanta, meaning supreme bliss and knowledge, showering peace and serenity, like cool breeze in a moonlit night. Ma is worshipped in this form in Kanchipuram (Tamil Nadu) India.
4. Kushmanda- The 4th night begins the worship of Kushmanda, possessed of eight arms, holding weapons and a mala or rosary. Her mount is a tiger and she emanates a solar like aura. "Kumbh Bhand" means to see cosmic vivacity in Pindi shape or knowledge of cosmic intricacies in human race.
5. Skandmata- Using a lion as a vehicle she holds her son, SKAND in her lap while displaying 3 eyes and 4 hands; two hands hold lotuses while the other 2 hands respectively display defending and granting gestures. Its said, by the mercy of Skandmata, even the idiot becomes an ocean of knowledge.
6. Kaatyayani- As mother, Kaatyayani stayed in the Ashram of sage Katyayan for penance, hence she named as Kaatyayani. This 6th Shakti is also astride a lion with 3 eyes and 4 arms. One left hand holds a weapon and the other a lotus. The other 2 hands respectively display defending and granting gestures. Her complexion is golden coloured.
7. Kaalratri- Black skin with bountiful hair and 4 hands, 2 clutching a cleaver and a torch, while the remaining 2 are in the mudras of "giving" and "protecting". Her vahana is a faithful donkey. The destroyer of darkness and ignorance, Kaalratri is the seventh form of Nav-Durga meaning scourer of darkness; enemy of darkness. Kaalratri's famous shrine is in Calcutta, India
8. Mahagauri ..... Four arms with the fairest complexion of all the Durga Shaktis. Peace and compassion radiate from her being and she is often dressed in a white or green sari. She holds a drum and a trident and is often depicted riding a bull.
9. Siddhiratri- Ensconced upon a lotus, most commonly, with 4 arms, and is the possessor of 26 different wishes to grant her bhakts. Siddhiratri's famous pilgrim centre, is located in Nanda Parvat in the Himalayas.
http://www.astrolozy.com/ninedurga.htm