Karthigai Deepam

Karthigai Deepam falls in the Tamil month of Karthigai on the day of the Karthigai nakshatra, and is the oldest recorded festival in Tamil literature. Rows of agal vilakku are lit along doorways, windows and courtyards.

For Murugan devotees it carries a second meaning: the six Karthigai stars are said to have nursed the six infant forms that became Murugan, which is why the month's Karthigai day is observed monthly as Masik Karthigai.

This is the vilakku festival. If you keep one lamp, this is the night it is lit — and it is the most common time of year to replace a worn one or add a second.