Pongal is the Tamil harvest festival, and it is often described as the one occasion on which the whole of Tamil Nadu keeps the same thing at the same time; it is a Tamil rather than a sectarian festival, observed by Tamils across religions and throughout the diaspora in Sri Lanka, Malaysia and Singapore. It is tied to the sun rather than the moon, beginning on the first of the Tamil month Thai, around 14 January, when the sun begins its northward course, and it takes its name from its central act: rice boiled with milk and jaggery in a new clay pot in the open, watched until it boils over, the overflow greeted with the shout "Pongalo Pongal!" and taken as a sign of coming plenty.
The festival runs over four days, each with its own object. Bhogi opens it with the burning of old and unwanted things, a clearing-out; Thai Pongal, the main day, is given to the Sun (Surya), to whom the fresh pongal is offered in thanksgiving for the harvest; Mattu Pongal honours the cattle whose labour made the harvest possible, their horns painted and garlanded; and Kaanum Pongal is for visiting family and outings. As a thanksgiving to the sun, the earth and the animals that sustain agricultural life, Pongal expresses a gratitude older than any sectarian theology, and its keeping across communal lines makes it a marker of Tamil identity itself.