In Jainism, Mahavir Jayanti, also known as 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.
He was born on the thirteenth day of the rising moon of Chaitra. The chronology accepted by all Jains places Mahavir's birth in 599 BCE.
Mahavira was born into royalty as the son of King Siddhartha and Queen Trishala. During pregnancy, Trishala 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 Trishala finally gave birth to Mahavira, the 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.