|Summary: What time zone are you in? It is all based on the Greenwich Mean Time.|
Greenwich Mean Time (GMT), Time Zones
Greenwich Mean Time (GMT) represents the starting point of every time zone in the world. Adopted in 1884, GMT is the average time it takes the earth to rotate noon to noon and is the center of the world time zone map. Measured by the Royal Observatory in Greenwich, England, where the Greenwich Meridian (also known as the Prime Meridian or Longitude Zero Degrees) is located, GMT is the international standard reference for time around the globe.
While much of the world follows Daylight Savings Time, where clocks are set ahead in the spring to make better use of sunny daylight hours and to save energy, GMT always remains the same. Each civilian time zone is measured relative to GMT and are usually designated in hourly increments. When moving west from the meridian one hour is subtracted from GMT for each time zone and then added when moving east. For example, GMT-5, or five hours earlier than GMT, is known as EST (US eastern zone). GMT+8 is eight hours ahead of GMT and is the Western Australia Standard time zone.
Zulu Time, the aviary and military name for GMT, designates each time zone with a single letter rather than the three letter designations typically used. US time zones typically known as EST, CST, MST, and PST are known to as Romeo, Sierra, Tango, and Uniform, respectively.