GMT(1) GMT stands for Greenwich Mean Time.
(2) 0° Longitude is taken as GMT.
(3) It is a common time for the entire world.
(4) It passes through Greenwich, England.
(5) It is 5 hours 30 minutes behind the IST.
IST
(1)IST stands for Indian Standard Time.
(2) 82°30' E longitude is taken as IST.
(3) It is a common time for entire India.
(4) It passes through the middle of India near Allahabad.
(5) IST is 5 hours 30 minutes ahead of the GMT