Question

what is significance of IST

Answer 1

IST ,Indian Standard Time, +5:30 he GMT.
If you check out the timezone map of world, you will notice that USA has 7 time zones and Russia has even more than that.
Suppose you are in some corner of USA and you are going to the another corner of USA, Due to some meeting work, well if you are in leftmost part of the country and want to go to the right side before 6 PM, if you will leave at 5:30 PM,(assume that you can reach to that area in 15 min) you get there in time according to the clock of your area BUT BUT the time of that area is different! you will be late!
This is what IST is set for. India has 4 different time zone but all of them are set to IST. All people of the country will experience the same time, there will be no doubts and clashes In the local times!
Hope the examples explains you well.

Answer 2

IST ,Indian Standard Time, +5:30 he GMT.
If you check out the timezone map of world, you will notice that USA has 7 time zones and Russia has even more than that.
Suppose you are in some corner of USA and you are going to the another corner of USA, Due to some meeting work, well if you are in leftmost part of the country and want to go to the right side before 6 PM, if you will leave at 5:30 PM,(assume that you can reach to that area in 15 min) you get there in time according to the clock of your area BUT BUT the time of that area is different! you will be late!