Onam (ഓണം) is the biggest and the most important festival of the state of Kerala.
It is a harvest festival and is celebrated with joy and enthusiasm all over the state by people of all communities.
According to a popular legend, the festival is celebrated to welcome King Mahabali, whose spirit is said to visit Kerala at the time of Onam.
Onam is celebrated in the beginning of the month of Chingam, the first month of Malayalam Calendar (Kollavarsham). This corresponds with the month of August-September according to Gregorian Calendar.
Carnival of Onam lasts from four to ten days. First day, Atham and tenth day, Thiruonam are most important of all. Popularity and presentation of rich culture of the state during the carnival made Onam the National Festival of Kerala in 1961.