by Corey
1 min read


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  • Life

Sometimes, I got emails from friends across the world. They usually kindly attach a timestamp at the end of the mail. One day, I got an email with CST in the timestamp from a guy I did not know before. This small tag confused me a lot because there are at least four time zones using CST as an abbreviation:

  • Central Standard Time (USA) UTC-6:00
  • Central Standard Time (Australia) UTC+9:30
  • China Standard Time UTC+8:00
  • Cuba Standard Time UTC-4:00

To precisely indicate the time zone, I strongly recommend the UTC (Coordinated Universal Time) standard, which is the basis for civil time today. UTC is the primary time standard by which the world regulates clocks and time. Here, Someone will doubt that whether we can use GMT (Greenwich Mean Time) to replace UTC. It is necessary to bear in mind that even though GMT and UTC share the same current time in practice, we still suggest using the UTC standard to denote time zone.

GMT is a country based time standard, whereas UTC is an internet based time standard. UTC is the time standard used for Internet and World Wide Web standards. It is also the basis of the satellite global positioning system (GPS). UTC is used by the Network Time Protocol, created to synchronize the clocks of many computers over the Internet. If we communicate via Internet, UTC is the best choice.

Well, back to the previous question. If we adopt UTC standard, we can make sure that the receiver got to know the exact time we refer to. For example, I live in Beijing, and my time zone is UTC+0800.

After all, using the proper medium to convey precisely what you really mean is the most important task in our life.