In the lunar Hindu calendar, Kartika begins with the new moon in November and is the eighth month of the year except in Gujarat, where it marks the new year that falls on Diwali. In the solar religious calendar used in Tamil Nadu, Kartikai begins with the Sun's entry into Scorpio and is the eighth month of the year.
In the Vaishnava calendar, Damodara governs this month.
The festival of Kartik Poornima (15th day Full Moon) falls in this month, celebrated as Dev Deepavali in Varanasi. This coincides with the nirvana of the Jain Tirthankara - Mahavira and the birth of the Sikh Guru Nanak Guru Nanak Jayanti. And also, the well known festival, for the god of Sabarimalai, Ayyappan's garland festival.