Question

what is IST and where does it passes it and what is it's important

Answer 1

Indian Standard Time (IST) is the timeobserved throughout India, with a time offsetof UTC+05:30. India does not observe daylight saving time (DSTu) or other seasonal adjustments. In military and aviation time IST is designated E* ("Echo-Star").[1]

Indian Standard Time is calculated on the basis of 82.30' E longitude, in Mirzapur, Uttar Pradesh, which is nearly on the corresponding longitude reference line.[2]

Answer 2

Hey user,
IST means Indian Standard Time and its value is (82° 30'E). It passes through Mirzapur in Uttar Pradesh.
IST is important because it is taken as the standard time for the whole country.
hope it helps:)