Onam is an annual Hindu festival with origins in the state of Kerala in India.

It falls in the Malayalam calendar month of Chingam, which in Gregorian calendar overlaps with August–September.

The festival commemorates the Vamana avatar of Vishnu, the subsequent homecoming of the legendary Emperor Mahabali and mythologies of Hinduism related to Kashyapa and Parashurama.

Onam is a major annual event for Malayali people in and outside Kerala. It is a harvest festival, one of three major annual Hindu celebrations along with Vishu and Thiruvathira, and it is observed with numerous festivities. Onam celebrations include Vallam Kali(boat races), Pulikali (tiger dances), Pookkalam (flower arrangement), Onathappan (worship), Onam Kali, Tug of War, Thumbi Thullal (women’s dance), Kummattikali (mask dance), Onathallu (martial arts), Onavillu (music), Kazhchakkula (plantain offerings), Onapottan (costumes), Atthachamayam (folk songs and dance), and other celebrations. It is the New Year day for Malayali Hindus.

Onam is the official state festival of Kerala with public holidays that start four days from Onam Eve (Uthradom) It is celebrated by Malayali diaspora around the world. Though a Hindu festival, non-Hindu communities of Kerala participate in Onam celebrations considering it as a cultural festival. However, some non-Hindus in Kerala denounce its celebration as a cultural event because they consider it as a religious festival.