Deepavali or Diwali means "a row of lights".It falls on the preceding day of the New Moon in the Malayalam month Thulam (October-November).For some it is a three-day festival.It commences with the Dhan-Teras, on the 13th day of the dark half of Kartik, followed the next day by the Narak Chaudas, the 14th day, and by Deepavali proper on the 15th day.
The legend behind this festival is that Narakasura, a demon, ruled the kingdom of Pradyoshapuram. Under his rule, the villagers suffered a lot of hardship as the demon tortured the people and kidnapped the women to be imprisoned in his palace. Seeing his wickedness, Lord Krishna set out to destroy the demon and the day Narakasura died was celebrated as Deepavali, the triumph of good over evil!
The Hindus usually awake early in the morning of deepavali around the brahmamuhurtam (3am) and the first ritual will be having an oil bath, which is an important feature of Deepavali. Hindus will be dressed in their new clothes on Deepavali.The houses would be decorated with oil lamps and children will play with firecrackers to celebrate the festival. On the first day, they would not go visiting but would stay at home to welcome the guests who visit them.
Deepavali may have deeper significance than what is popularly believed. At the time of the festival the sun is in the house of Thulam (Libra ie. the scales) which signifies commerce, and hence the association of Deepavali with merchants and the Goddess of wealth. The darkness and light symbolize ignorance and knowledge respectively.