Naraka Chaturdashi is an annual Hindu festival observed on Chaturdashi, the fourteenth day of the Krishna Paksha, in the Hindu calendar month of Ashvin according to the amanta tradition, or Kartika according to the purnimanta tradition. It is the second day of the five-day festival of Diwali, also known as Deepavali.
The festival is known by several regional names, including Kali Chaudas, Narak Chaudas, Roop Chaudas, Choti Diwali, Narak Nivaran Chaturdashi and Bhoot Chaturdashi. The name Narakasura is sometimes interpreted in connection with the Sanskrit roots nr or nar, meaning "man", and aka, associated with unhappiness, with the term itself sometimes rendered as referring to hell or a demon from hell.
According to Hindu literature, the day commemorates the slaying of the asura (demon) Narakasura by Krishna and his consort Satyabhama. The narrative forms the central legend associated with the observance and connects it to the wider symbolism of Diwali as the triumph of light over darkness.
The day is typically marked by early morning religious rituals, followed by festivities later in the day. Customs associated with Naraka Chaturdashi vary across regions of India and within different Hindu communities, but commonly include ceremonial bathing, prayers and the lighting of lamps as part of the broader Diwali celebrations.
Adapted from the English Wikipedia article on Naraka Chaturdashi.