GMT and IST Full Form:
GMT stands for Greenwich Mean Time, and IST stands for Indian Standard Time.

Greenwich Mean Time (GMT):
- GMT is the mean solar time at the Royal Observatory in Greenwich, London.
- It is used as the standard time against which all other time zones in the world are referenced.
- GMT is based on the Prime Meridian, which runs through Greenwich, England.

Indian Standard Time (IST):
- IST is the time observed throughout India and Sri Lanka.
- It is 5 hours and 30 minutes ahead of GMT.
- IST is calculated based on the 82.5° E longitude, which passes through the city of Allahabad in India.

Key Differences:
- GMT is the baseline time standard against which other time zones are compared, while IST is the time standard used in India and Sri Lanka.
- GMT is based on the Prime Meridian in Greenwich, while IST is based on the 82.5° E longitude.
- GMT does not observe Daylight Saving Time changes, while IST does not have any DST adjustments.
In conclusion, GMT and IST are important time standards used globally and regionally, respectively. Understanding the differences between these two time standards is essential for coordinating activities across different time zones.

GMT Greenwich Mean Time and IST Indian Standard Time