Tripurari Purnima, or Tripura Poornima, is the full moon day in the Kartik month in a traditional Hindu calendar. In 2015, the date of Tripuri Purnima is November 25. The day celebrates the victory of Lord Shiva over the demon Tripurasura and the destruction of the three cities – Tripuri – made by demons. The day is also known as Kartik Poornima and Deo or Dev Diwali.
The legend has it that a powerful demon named Tripuri or Tripurasura built three impregnable cities of gold, silver and iron with the blessing of Lord Shiva. The demon became so powerful and his inflated ego knew no bounds and started attacking and tormenting humans and demi gods (devas). Brahma and Vishnu failed to contain Tripurasura who was armed with several boons from Shiva.
Finally, the task of annihilating the demon fell on Lord Shiva and after three days of fight, Lord Shiva killed Tripurasura and destroyed the three cities – Tripuri. This great victory happened on the full moon day in Kartik month and therefore the day is celebrated as Tripuri Poornima and it is also the day of Deo Diwali or Dev Diwali – the Deepavali of Devas as they were liberated from the hands of the powerful demon.
Lighting of lamps in temples and homes in the evening after sunset in honor of Shiva is a major event on the day.