Dev Deepavali or Dev Diwali is a famous festival celebrated on auspicious Kartika Pournami (Full moon day of the month Kartika) to mark victory of Lord Shiva over demon Tripurasur, that is why also known as Tripurari Purnima.  

On Dev Deepawali, devotees take a holy dip in sacred rivers also known as (Karthik Snan) and lit earthen lamps or Diya(s) in the evening at homes, temples and on the banks of rivers.

It is believed that Lord Karthikeya son of Lord Shiva & Goddess Parvati took birth on this day. It is also believed that Lord Vishnu took his first incarnation – Matsya (Fish) Avatar (the first of Dasha Avatar – the ten incarnations) on this auspicious day.

Dev Diwali has been celebrated in a grandeur in the holy city Varanasi. Thousands of devotees take holy dip in sacred Ganga River and lit thousands of earthen lamps along the banks of Ganga and perform a grand Ganga Aarati.