Navratri is one of the holy festivals of hinduism. It is a festival of nine nights, during which we worship goddess of shakti.
When the supreme being begins to manifest its cosmic energy, it is variously known as Sakti, Devi or Divine Mother, who assumes many forms according to the tasks to be preformed by her. She is also known as Durga, Lakshmi or Sarawati in her destructive, protective, and knowledge giving roles respectively. These three aspects of the Divine Mother are worshipped during Devi Navaratri puja, the nine nights.
Navratri festival is observed twice a year, once in the month of Chaitra and then in Aswayuja. It lasts for nine days in honour of the nine manifestations of Durga. During Navaratri (the word literally means "nine nights") devotees of Durga observe a fast. Brahmins are fed and prayers are offered for the protection of health and property.
Durga or the destructive aspect of the divine mother is worshipped during the first three nights. On the succeeding three knights, her protective aspect of Lakshmi and on the last three nights, her knowledge aspect or Saraswati are worshipped. The significance of this order is that first durga destroys all the evil propensities lurking in the minds of her devotees; then lakshmi implants divine qualities in the devotees' minds and finally saraswati bestows true knowledge to her devotees. The tenth day known as Vijaya Dasami, commemorates the victory of knowledge over ignorance of goodness over evil.