What is the meaning of greenwich mean time?

Answer 1

Greenwich Mean Time (GMT) is the time of day at any point on the Greenwich meridian (the zero degree line of longitude). It is from this time that all other time zones on earth (+ or -) are compared therefore if you want to communicate things that happen all round the earth you use GMT to communicate this (rather than your local time) to avoid confusion and the need for calculations.

Answer 2

Before the adoption of standard times in the 19th and 20th centuries, the time in each city was the mean time for that city, which is noon at the mean (average) time that the sun is at its highest point in the sky as seen from that city every day for a year. The meridian (line of longitude) that passes through Greenwich, England, the location of England's Royal Observatory, was chosen as the Prime Meridian, which is 0° longitude. In 1960, Coordinated Universal Time (UTC) replaced GMT as the time at the Prime Meridian, which is still the meridian passing through Greenwich. GMT and UTC are often used interchangeably, even though their definitions are not exactly the same.

Answer 3

The most commonly used and widely accepted abbreviation of Greenwich Mean Time is GMT. Greenwich Mean Time is always absolute and does not change seasonally.