World City Clock Time Zone Listing

What are World City Time Zones?

Shows the world time and date for cities in all time zones.

A time zone represents an offset applied to Greenwich Mean Time (GMT) to obtain local time. The offset might vary throughout the year, if daylight savings time (DST) is used, or might be the same all year long. Typically, regions closer to the equator do not use DST. If DST is in use, then specific rules define the point at which the offset changes and the amount by which it changes.

A time zone is a region of the globe that observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries of countries and their subdivisions instead of strictly following longitude because it is convenient for areas in close commercial or other communication to keep the same time.

Why are there 24 time zones?

A time zone is a place or area where the same standard time is observed. The planet is divided longitudinally into time zones, with approximately 15 degrees apart from each hour difference. Since several nations have half hour time zones, the planet has more than twenty-four times that. The point of departure at which Synchronized Universal Time (UTC) begins is the Prime Meridian (zero longitude). The International Date Line (IDL), located 180 degrees longitude, delineates from one day to the next; time moves incrementally as one travels west of the IDL.

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