Karthigai Deepam is the oldest festival of South India, which is also the most elaborate and the most important festival. Karthigai Deepam falls in the Tamil month of Karthigai when the star Krithigai is on the ascendant and usually occurs on a full moon day. This festival is also called as "the Festival of Lights".
Evidence from Tamil literature proves that this festival is one of the oldest in the state. In ancient Tamil literature, the oldest available work Tolkappiyam gives in concise verse form rules for Tamil grammar as well as other topics.
In another epic "Jeevakachintamani" written by a Jain poet, Thiruthakka Thevar, the poet describes how people celebrated the Karthigai Deepam festival. In other ancient Tamil literature of the Sangam period, the Karthigai Deepam festival is described vividly.
In "Karnarpadu", the poet in one of the stanzas, describes how in the Tamil month of Karthigai, the lamps lit by people blossomed on earth, bringing rain in its wake. This festival is considered as the extension of the Deepavali festival. In some houses, they double the number of lamps every day from the day of Deepavali and this way, they end up with a number of lamps on the day of Karthigai Deepam.
On this day, people clean their houses and draw 'Kolams' (Rangoli) in front of the house and also place some lamps on it. They place the lamps in the puja room and light them and after the 'Deeparathana' the lamps are moved to the different places in the house. The lamps glow all over the streets on this day.