Navaratri is an amalgamation of various themes, with the common theme of the victory of good over evil. According to some legends, Vijayadashami or Dusshera is celebrated on the day Lord Ram kills Ravana.
According to a Puranic legend, the mighty demon Mahishasura defeated the gods and their king, Indra.
They then approached Brahma, Vishnu and Maheshwar, who decided to destroy the demon. So they all combined their energies, and gave rise to Shakti and appealed to Goddess Durga to come to their aid.
Equipped with lethal weapons and riding a ferocious lion, the Goddess in all her awesome majesty, destroyed the evil one without much ado. The 10th day, on which the goddess kills Mahishasura, is celebrated as Dusshera or Vijayadashami as the victory of good over evil. Dusshera (tenth day) is one of the significant Hindu festivals, celebrated with pomp and fervor all over the country.
On the tenth day, the Vijayadasmi day, colossal effigies of Ravana, his brother Kumbhkarna and son Meghnadh are placed in vast open spaces. Rama, accompanied by Sita and his brother Lakshmana, arrive and shoot arrows of fire at these effigies. The result is a deafening blast, enhanced by slogans of triumph.
In burning the effigies the people are asked to burn the evil within them, and thus follow the path of virtue and honesty. On this day in the famous Ramleela grounds in Delhi, huge effigies of the ten-headed demon king Ravana, Meghanath, his son, and Kumbhakarna, his brother, stuffed with explosive materials are torched by an arrow to symbolize the ultimate triumph of good over evil.