why Onam festival is celebrated?

Onam a significant festival celebrated in Kerala marks the homecoming of King mahabali it is a harvest festival celebrated with enthusiasm by all malayalees and keralities

According to Hindu mythology generous and prosperous ruler Mahabali who was sent to the neither world by lord Vishnu 

However Vishnu granted him the opportunity to visit Kerala once a year this year Onam will be celebrated on 29th August 2023

As per Hindu mythology King mahabali so generous and considered as a great ruler of Kerala 

The Kingdom was so prosperous and his reign people of kingdom where happy and they loved  

Their King the enemy of demons that is wanted to end the rule of mahabali from Earth.

They were jealous of him asking mahabali defeated them to become the king they send lord Vishnu to King mahabali

Lord Vishnu took a form of vamana Avatar and went to King mahabali to test him and ask for 3 feet of land from mahabali 

He agreed on that so lord Vishnu covered all the world's into states and then ask him for a place to put his third step 

Mahabali requested vamana to put his third step on his head which took him to the nether world but this made lord Vishnu happy and he was pleased by his devotion