Holi Festival is a two-day celebration that occurs on the Purnima Full Moon of the Hindu calendar. It is closely related to the mythological stories of the King Prahlad and Lord Krishna. According to the Hindu mythology, the king of demons, Hiranyakashipu, was bestowed with a gift, which made him immortal. Attacking the Earth and Heavens, he demanded that people worship him instead of praying to Gods. However his son, Prahlad, continued praying to Lord Vishnu. Prahlad was saved by God twice when his father tried to kill him. It was his sister, Holika, who was burnt to death in the fire. Since then Holi Festival is observed to commemorate the burning of Holika.
Another legend related to the festival involves Lord Shiva, one of the major gods in Hindu mythology who was famous for his meditative nature. In order to break His meditation so that Lord Shiva could evince interest in the worldly matters and fight the demons who were threatening the Heaven, the God of Love, Madana or Kamadeva, shot a love arrow at Him. However the wrath of Lord Shiva immediately reduced him to ashes. Holi is celebrated in south India to remember the sacrifices of Kamadeva.
Holi is also connected with the legend about the divine love between Krishna and Radha. When dark complexioned child Krishna complained to his mother about Radha's fair color, mother Yashoda advised him to sprinkle colors on Radha's face. This ritual gave rise to Holi festival in Vraj where Sri Krishna used to play Holi with Sri Radha and the Gopis (her accomplices) with colors like abir, gulal etc.
In Bengal, Puri, Vrndavan and Mathura the holiday is also celebrated as the Sri Krishna Chaitanya's birthday. Sri Krishna Chaitanya was a famous religious preacher and a social reformer born in 15th century in West Bengal. He preached the equality of man cutting across caste and class barriers and carried the message of love and devotion for Lord Krishna.