A world clock is a clock which displays the time for various cities around the world. The display can take various forms:

The clock face can incorporate multiple round analogue clocks with moving hands or multiple digital clocks with numeric readouts, with each clock being labelled with the name of a major city or time zone in the world. The World Clock in Alexanderplatz displays 146 cities in all 24 time zones on its head.^[2]^[3]
It could also be a picture map of the world with embedded analog or digital time-displays.
A moving circular map of the world, rotating inside a stationary 24-hour dial ring. Alternatively, the disc can be stationary and the ring moving.
Light projection onto a map representing daytime, used in the Geochron, a brand of a particular form of world clock.

There are also worldtime watches, both wrist watches and pocket watches. Sometime manufacturers of timekeepers erroneously apply the worldtime label to instruments that merely indicate time for two or a few time zones, but the term should be used only for timepieces that indicate time for all major time zones of the globe.

References

[edit]

^ Helmut Caspar: Ärger mit der Weltzeituhr am Alex. Städtenamen sind nicht korrekt. In: Märkische Allgemeine Zeitung, 24/25 December 1997.
^ Team, Berlin Hub (2016-04-01). "The History Of The World Clock In 1 Minute". Culture Trip. Archived from the original on 2022-12-09. Retrieved 2022-12-09.
^ "Berlin: A World Clock for those who Could Not Travel the World". The Berlin Spectator. 2021-03-12. Archived from the original on 2022-12-01. Retrieved 2022-12-09.

Time

Key concepts

Measurement
and standards

Chronometry	UTC UT TAI Unit of time Orders of magnitude (time)
Measurement systems	Italian six-hour clock Thai six-hour clock 12-hour clock 24-hour clock Relative hour Daylight saving time Chinese Decimal Hexadecimal Hindu Metric Roman Sidereal Solar Time zone
Calendars	Main types Solar Lunar Lunisolar Gregorian Julian Hebrew Islamic Solar Hijri Chinese Hindu Panchang Maya List
Clocks	Main types astronomical astrarium atomic quantum hourglass marine sundial watch mechanical stopwatch water-based Cuckoo clock Digital clock Grandfather clock History Timeline

Philosophy of time

Human experience
and use of time

Time in science

Geology	Geological time age chron eon epoch era period Geochronology Geological history of Earth
Physics	Absolute space and time Arrow of time Chronon Coordinate time Instant Proper time Spacetime Theory of relativity Time domain Time translation symmetry Time reversal symmetry
Other fields	Chronological dating Chronobiology Circadian rhythms Clock reaction Glottochronology Time geography

v t e Time measurement and standards
Chronometry Orders of magnitude Metrology
International standards	Coordinated Universal Time offset UT ΔT DUT1 International Earth Rotation and Reference Systems Service ISO 31-1 ISO 8601 International Atomic Time 12-hour clock 24-hour clock Barycentric Coordinate Time Barycentric Dynamical Time Civil time Daylight saving time Geocentric Coordinate Time International Date Line IERS Reference Meridian Leap second Solar time Terrestrial Time Time zone 180th meridian
Obsolete standards	Ephemeris time Greenwich Mean Time Prime meridian
Time in physics	Absolute space and time Spacetime Chronon Continuous signal Coordinate time Cosmological decade Discrete time and continuous time Proper time Theory of relativity Time dilation Gravitational time dilation Time domain Time-translation symmetry T-symmetry
Horology	Clock Astrarium Atomic clock Complication History of timekeeping devices Hourglass Marine chronometer Marine sandglass Radio clock Watch stopwatch Water clock Sundial Dialing scales Equation of time History of sundials Sundial markup schema
Calendar	Gregorian Hebrew Hindu Holocene Islamic (lunar Hijri) Julian Solar Hijri Astronomical Dominical letter Epact Equinox Intercalation Julian day Leap year Lunar Lunisolar Solar Solstice Tropical year Weekday determination Weekday names
Archaeology and geology	Chronological dating Geologic time scale International Commission on Stratigraphy
Astronomical chronology	Galactic year Nuclear timescale Precession Sidereal time
Other units of time	Instant Flick Shake Jiffy Second Minute Moment Hour Day Week Fortnight Month Year Olympiad Lustrum Decade Century Saeculum Millennium
Related topics	Chronology Duration music Mental chronometry Decimal time Metric time System time Time metrology Time value of money Timekeeper

See also

References