Why do Eid dates differ in India & Saudi Arabia & when will India celebrate Eid ul-Fitr?

Eid dates differ in India and Saudi Arabia due to crescent moon sighting. In India, it's declared only after crescent moon is physically sighted on Ramadan's 29th. Saudi Arabia also follows moon sighting, but often confirms the sighting earlier due to its geographical position. Saudi Arabia will celebrate Eid ul-Fitr on March 20, while India will celebrate on March 21.