Question

Define GMT (Greenwich mean time). Also why is standard time necessary in India? ​

Answer 1

India's time zone is UTC/GMT (Coordinated Universal Time/Greenwich Mean Time) +5.5 hours. It's referred to as Indian Standard Time (IST). What's unusual is that there is only one time zone across the whole of India. The time zone is calculated according to the longitude of 82.5° E.

Answer 2

Indian Standard time (IST) is the time zone observed throughout India, with a time offset of UTC+05:30. India does not observe daylight saving time or other seasonal adjustments. In military and aviation time IST is designated E* ("Echo-Star").[1] It is indicated as Asia/Kolkata in the IANA time zone database.