'Karthika Deepam' or 'Karthikai Vilakkidu' is a festival of lights that is observed by Hindus in Sri Lanka. It falls in the month of Kārttikai (mid-November to mid-December) as per Tamil calendar.
Rows of 'Agal Vilakku' (Clay Oil lamps) are lit in every house. Karthigai is essentially a festival of lamps. The lighted lamp is considered an auspicious symbol. It is believed to ward off evil forces and usher in prosperity and joy. While the lighted lamp is important for all Hindu rituals and festivals, it is indispensable for Karthigai.