GMT Full Form is Greenwich Mean Time. Time in the world is measured on the basis of Greenwich Mean Time or GMT. Greenwich Mean Time or Average Time is the time taken for the Earth to rotate on its axis in twenty-four hours. The village of Greenwich, on the basis of which the foundation of Greenwich time is laid, is located in the middle of the Earth time map in England.
However, GMT was replaced with atomic time on 1 January 1972, which also accounts for one thousand-millionth of a second. The reason for this was that the axis of the earth does not stay at the same speed and it takes more or less time to rotate in its orbit. The time based on atomic clocks is called Coordinated Universal Time (UTC). Despite this, time is measured in the world only on the basis of GMT. GMT is also known as Zulu Time.
GMT itself is officially used in winter in England. In the summer, ‘British Summer Time’ is used there. GMT is similar to the times in Western Europe. Historically, GMT was the basis of two different standards. In the astronomical method before 1925, the time of 12 noon was called Zero Hour, while at the same time in the normal life, the night 12 was considered as Zero Hour.
Later, night time itself was recognized as an astronomical and common life. Instead of these, there is no such duality in Universal Time (UT). In both the time standards, twelve o’clock is called zero hour.