Mahabali was the grandson of Prahlada and son of Hiranyakashyapa who was killed by Vishnu in his Narasimha Avatara. Prahlada had great faith in Vishnu and Mahabali had become a devotee of Lord Vishnu due to his grandfather Prahlada. Mahabali gradually became a powerful ruler all the realms including heaven and earth with the guidance of his guru Shukracharya. Gods saw this as treat and asked Lord Vishnu for help. Lord Vishnu stopped Mahabali as boon given to Aditi. By seeing Gods becoming weak and Gods becoming stronger, Aditi prayed to Lord Vishnu and did Vrata with pure heart. Lord Vishnu agreed to help King Indra.
Mahabali was going strong day by day and he thought there is no one greater than him. He was proud of himself and he thought he can grant anyone that is asked to him. In the meantime he was performing Viswajith Yagam on the banks of the Narmada River on the advice of his guru Shukracharya. Mahabali declared he would give anything that was asked to him during this time. Lord Vishnu was born as Vamana to Aditi. Taking advantage of the Yagna, Vamana when asked what gift he wants, he said he need place equivalent to this three paces of his feet. Shukracharya advices not give the wish as he is Lord Vishnu. Mahabali begged for pardoned to his Guru and gave the promise. Vamana grew in size and measured all of the earth. He kept his second foot on heaven and third on Mahabli’s head. As a last gift, Mahabali was granted permission to visit his kingdom once a year.
Onam is celebrated on the Chingam month of Malayalam calendar. In English caledner it comes in the month of August/September. It is mainly celebrated in Kerala.
Onam is celebrated for ten days. During the festival Onapookkalam, the floral carpet made of different varieties of flowers is made. Onam sadya is traditional meals served in plantain leaves which consist of about 26 dishes. Boat races are associated with Onam. Onakkodi is the tradition of buying and wearing new clothes of Onam. Onakkalikal various forms of games and dances are performed. Atham is the first day of Onam; Athachamyam is performed on this day. Chithira, second day of Onam, people clean their houses. Chodhi, the third day is marked for shopping. Pookkalam competition is started on the Vishakam the fourth day. On Anizham the fifth day of Onam, Vallamkali is started. Thriketa is the sixth day of Onam. Moolam, Pooradam, Uthradom and Thiruvonam are 7th to 10th days of Onam respectively.