Goddess manifested herself in the fourth form of divinity named Kushmanda. Therefore on the fourth day of navratri we worship Goddess Kushmanda. Devi Kushmanda is known for living inside the sun, so is her appearance. Indeed she is as luminous and bright as sun. She is the one who is nurturing the universe like sun. The universe is the smile of the Goddess.
On the third day of navratri we worship Goddess Chandraghanta. Chandraghanta is the married form of Devi Parvati. In sanskrit Chandra is the 'moon' and Ghanta is 'bell'. After marriage she adores the moon on her head which looks like a bell. Thus she named Chandraghanta.
Second day of navratri is the day of Goddess Brahmacharini. Brahmacharini is the incarnation of Goddess who did great penance. In sanskrit Brahm is the 'ultimate reality' and Charini is 'to follow, behave'. thus Brahmacharini means the one who follows the path towards the parabrahman, the absolute one. The fruit of her hard austerities is the "Shiva", she got married to him.
First day of navratri is the day of Goddess Shailputri. Shailputri is the incarnation of Goddess again after leaving the body of Sati (wife of Lord Shiva). Devi Durga took birth in the house of King of mountains Himalaya and his consort Maina. In sanskrit shaila is mountain and putri is daughter, thus shailputri means the daughter of mountain. called Shailputri. Later she got married to Lord Shiva.
As we know navratri is for nine days, so the mantra sadhana is for 9 days. Each one of the nine days is dedicated to a particular Goddess, Thus nine goddesses for nine days. Each day has a new mantra. One should recite the mantra of the day along with the durga mantra. Blog gives the information about are the mantras of the each goddess.
Goddess Saraswati is the intelligence and wisdom behind the creation. She is devi of knowledge known as 'Vidya ki Devi'. She also represents music, arts, speech. The goddess of creativity signifies the sattva guna from the three gunas. She is the Jnana shakti which purifies the mind and establish one in true self.