In Jainism, Mahavir Janma Kalyanak is the most important religious holiday. It celebrates the birth of Mahavira, the last Tirthankara. On the Gregorian calendar, the holiday occurs either in March or April.
Mahavira was born on the thirteenth day of the rising moon of Chaitra. His exact age remains a matter of dispute as the Jain community has not reached a consensus as to the year he was born. The Digambar school of Jainism believe that Mahavira was born in 615 BC while Svetambara Jains traditionally believe that he was born in 599 BC.
Mahavira was born into royalty as the son of King Siddhartha and Queen Trisala. During pregnancy, Trisala was believed to have had a number of auspicious dreams, all signifying the coming of a great leader. The exact number of dreams differs according to the school of Jainism; Svetambaras generally believe that the actual number is fourteen while Digambaras claim sixteen instead. Regardless, the astrologers that interpreted these dreams claimed that the child would become either an emperor or a Tirthankar. It is said that when Trisala finally gave birth to Mahavira, the Hindu god-king Indra bathed the newborn himself with celestial milk, a ritual essentially marking him as a Tirthankar.
Local statues of Mahavira are given a ceremonial bath called the abhisheka. During the day, many Jains engage in some sort of charitable act in the name of Mahavira while others travel to temples to meditate and offer prayers. Lectures are typically held in temples to preach the path of virtue as defined by Jain doctrine. Donations are collected in order to promote charitable missions like saving cows from slaughter or helping to feed poor people. Ancient Jain temples across India typically see an extremely high volume of practitioners come to pay their respects and join in the celebrations.