Vijaydashmi is the tenth day of the Ashwin month(removed the full stop here) or the last day of the Navratri or Durga Puja festival. This auspicious day symbolizes the triumph of Good over Evil and is celebrated differently in many parts of India.
In Gujarat it is celebrated as the last day of Navratri, in West Bengal it is celebrated as the day Goddess Durga killed Asura(Demon) Mahishasura. In northern states like Uttar Pradesh this festival is called Dussehra as on this eventful day, King Rama, the eighth incarnation of Lord Vishnu killed Ravana, the ten-headed King of Lanka who had abducted his wife Sita. This day is also considered auspicious to set date for weddings.