Significance
Janmashtami celebrates the birth of Lord Krishna, the eighth avatar of Vishnu, born at midnight in Mathura to Devaki and Vasudeva to end the tyranny of Kansa. He is the divine teacher of the Bhagavad Gita.
It is among the most joyously observed festivals across India.
Rituals
Devotees fast through the day and celebrate Krishna's birth at midnight (nishita kaal) with abhishek of the infant idol, bhajans, jhankis and the swinging of the cradle. Dahi Handi — the human-pyramid breaking of a curd pot — is enacted the next day.
How the date is fixed
Janmashtami falls on the Ashtami of the Krishna paksha of Bhadrapada (amanta Shravana), decided by the tithi at midnight (nishita), Krishna's birth-hour, so the nishita muhurat is shown above for your location.