Ekadashi
Ekadashi is the 11th tithi of each lunar fortnight, sacred to Vishnu and widely kept as a fast. It comes twice a month, about 24 times a year, and the fast is broken the next morning, on Dwadashi.
Also known as: Ekadasi, Gyaras, Agiyaras, Ekadashi vrat, Ekadashi fast
Each paksha has an Ekadashi, so there is a Shukla and a Krishna Ekadashi every month: 24 in a normal year and 26 when there is an Adhik maas. Each has its own name and story, such as Nirjala, Devshayani, Devuthani (Prabodhini) and Vaikuntha Ekadashi. Devotees fast or avoid grains, and pray to Vishnu.
The fast day follows the tithi, with extra rules. Smarta panchangs generally keep Ekadashi on the day it prevails at sunrise. Vaishnava traditions, including ISKCON, also check the pre-dawn period (arunodaya): if Dashami still touches it, they fast the next day. That is why two Ekadashi dates are sometimes listed, one Smarta and one Vaishnava. Our Panchang names each Ekadashi on its Smarta date, the one whose parana falls in Dwadashi.
The fast is broken (parana) on Dwadashi, after sunrise and before Dwadashi ends, avoiding its first quarter, called Hari Vasara. Panchangs give a parana window because breaking the fast too early, or after Dwadashi has ended, is traditionally considered incomplete.