An international time zone is a system that provides us with a way of knowing what time it is in any part of the world at any time. It works longitudinally to the globe with equal lines running from the north pole to the south pole being divided into 24 zones which makes up a single day or 24 hours.
The system originated in Britain and is centered on the UTC (Universal Time, Co-ordinated) - (Greenwich Mean Time), system located at the Royal Observatory located in the Greenwich area of London.
What is UTC?
UTC is also sometimes called Z or Zulu time. A time may be written as e.g. 21:45Z with the Z indicating UTC. The "Z" is for "zero", and "Zulu" is the two-way radio pronunciation of "Z". It comes from the nautical system in which each time zone was assigned a letter.
Time zones east of UTC and west of the International Date Line are specified by the number of hours ahead of UTC (e.g. UTC+4); zones west of UTC and east of the Date Line are specified by the number of hours behind UTC (e.g. UTC-6). Crossing the Date Line going eastward, clocks are turned back a full 24 hours, and vice versa in the opposite direction. (Note: The total span of time zones covers more than 24 hours because the Date Line jogs westward and eastward to keep certain national island groupings on the same calendar day, although they are not within a single time zone.)
International time zones conversion
It is important to note that Zulu time is unaffected by Daylight Saving Time. Therefore, when Daylight Saving Time is in effect, Zulu time is one hour behind UTC. Consider this when converting time at certain times of the year.
use an international times zones conversion to work out what time it is where they currently are, what time it is at home in case they wish to call back and what time to arrange their day around.