It is celebrated on Chathayam day during the Onam season in Chingam month of Malayalam calendar.
It marks the birthday of Narayana Guru, a saint and a social reformer of India who fought against the caste system of Hindu religion.
As a state festival, the day is a public holiday for schools and offices, including banks, in Kerala.
Guru's birthday is celebrated on the Chathayam asterism of the Malayalam month of Chingam (Leo).
In a society broken into fragments by casteism and economic inequality, he emphasised the motto of 'one caste, one religion and one god.'