Today, 26 March 2013 is Holika Dahan, Hutashani Purnima, Kamadahanam, Madana Purnima. It falls on the day before Holi festival in almost all parts of India. As we all know, Falgun Purnima (Phalguna Pournami) is observed as Holi festival.
In South Indian states like Andhra Pradesh, Karnataka and Tamil Nadu, Holika Dahan is observed as Kamadahanam. Instead of Holika, Kamadeva (Lord of Love in Hinduism) is burnt into ashes. The holy ash is distributed among the villagers. They keep the ash at their puja place.
Holika Dahan has the reference in Puranas. The story of Holika Dahan is associated with demon Hiranyakashipu, his sister Holika and Prahlada.
Kamadahanam story is associated with the marriage of Lord Shiva and Goddess Parvati, prior to which Lord Shiva burns Kamadeva into ashes.