Overview
Govardhan Puja (IAST: Govardhana-pūjā), also known as Annakut, meaning a "mountain of food", is a Hindu festival celebrated on the first lunar day of the bright fortnight of the month of Kartika. It falls on the fourth day of Diwali and is observed by devotees across India and abroad.
On this day, devotees worship an image of Govardhan Hill traditionally fashioned out of cow dung. A large variety of vegetarian dishes is prepared and offered to Krishna as a mark of gratitude. The mountain of food, presented before the deity, is a metaphorical representation of Govardhan Hill itself, and the offering is intended as a ritual remembrance and a renewal of faith in taking refuge in God.
For Vaishnavas, the festival commemorates the episode narrated in the Bhagavata Purana in which Krishna lifted Govardhan Hill to provide the villagers of Vrindavan shelter from torrential rains. According to the tradition, the people of Vrindavan had earlier worshipped Indra for rain. The incident is understood within the tradition as symbolising the protection offered by God to devotees who take singular refuge in him.
Govardhan Puja is observed by most Hindu denominations and holds particular importance in several Vaishnava sects, including the Pushtimarg Sampradaya, the Gaudiya Sampradaya and the Swaminarayan Sampradaya. In temples associated with these traditions, elaborate displays of food are arranged before the deity as part of the Annakut observance.
References
Adapted from the English Wikipedia article on Govardhan Puja.