A time zone is a region of the globe that observes a uniform standard time for legal, commercial . "WST", and "CST", but these are not part of the international time and date standard ISO and their use as sole designator for a time zone. current local time around the world with our customizable international clock. the western boundary of the UTC timezone, up to the International Date Line. International Standard ISO specifies numeric representations of date and time. It helps to avoid confusion caused by the many different.
A time zone is a region of the globe that observes a uniform standard time for legal, commercial . "WST", and "CST", but these are not part of the international time and date standard ISO and their use as sole designator for a time zone. current local time around the world with our customizable international clock. the western boundary of the UTC timezone, up to the International Date Line. The International Date Line (IDL) is an imaginary line on Earth's surface defining the boundary between one day and the next. The International Date Line is located halfway around the world from the prime meridian (0° longitude) or about ° east (or west) of Greenwich, London.
current local time around the world with our customizable international clock. the western boundary of the UTC timezone, up to the International Date Line. The Time Zone Converter converts times instantly as you type. Convert between major world cities, countries and timezones in both directions. This free time zone calculator converts between different time zones around the Time: (24 hours, e.g. ). From: (UTC) International Date Line West.
A time zone is a region of the globe that observes a uniform standard time for legalcommercialand social purposes. Time zones tend to follow the boundaries of countries and their subdivisions instead of longitude, because it is convenient for areas in close commercial or other communication to keep the same time.
Some higher latitude and temperate zone countries use daylight saving time for part of the year, typically by adjusting local clock time by an hour. Many land time zones are skewed toward the west of the corresponding nautical time zones. This also creates a permanent daylight saving time effect. Before clocks were invented, it was common practice to mark the time of day with apparent solar time also called "true" solar time — for example, the time on a sundial — which was typically different for every location and dependent on longitude.
When well-regulated mechanical clocks became widespread in the early 19th century,  each city began to use local mean solar time. Apparent and mean solar time can differ by up to around 15 minutes as described by the equation of time because of the elliptical shape of the Earth's orbit around the Sun eccentricity and the tilt of the Earth's axis obliquity. Mean solar time has days of equal length, and the difference between the two sums to zero after a year.
Greenwich Mean Time GMT was established datewhen date Royal Observatory was built, as an aid to mariners to determine longitude at sea, providing a standard reference time while each city in England kept a different local time. Local solar time became increasingly inconvenient as rail transport and telecommunications improved, because clocks differed between places by amounts corresponding to the differences in their geographical longitudes, which varied by four minutes of time for every degree of longitude.
For example, Bristol is about 2. The first adoption of a standard time was on December 1,in Great Britain by railway companies using GMT kept by portable chronometers. This quickly became known as Railway Time. About August 23,time signals were first transmitted by telegraph from the Royal Observatory, Greenwich. Some British clocks from this period have two minute hands—one for the local time, one for GMT.
Improvements in worldwide communication further increased the need for interacting parties to communicate mutually comprehensible time references to one another. The problem of differing local times could be solved across larger areas by synchronizing clocks worldwide, but in many places that adopted time time then differ markedly from the solar time to which people were accustomed. On November 2,the then British colony of New Zealand officially adopted a standard time to be observed throughout the colony, and was perhaps the first country to do so.
This standard was known as New Zealand Mean Time. Timekeeping on the American railroads in the midth century was somewhat confused. Each railroad used its own standard time, usually based on the local time of its headquarters international most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had a clock for each railroad, each showing a different time. Charles F.
Dowd proposed a system of one-hour standard time zones for American railroads aboutalthough he published nothing on the matter at that time and did not consult railroad officials until In he proposed four ideal time zones having north—south bordersthe first centered on Washington, D. Dowd's system was never accepted by American railroads. Date, U. Allen, the editor of the Traveler's Official Railway Guide.
For example, the border between its Eastern and Central time zones ran through DetroitBuffaloDateAtlantaand Charleston.
It was inaugurated on Sunday, November 18,also called "The Day of Two Noons",  when each railroad station clock was reset as standard-time noon was reached within each time zone. The confusion of date came to an end when Standard zone time was formally adopted by the U. Congress in the Standard Time Act of March international, The first known person to conceive of a worldwide system of time zones was international Italian mathematician Quirico Filopanti.
He introduced the idea in his book Miranda! He proposed 24 hourly time zones, which he called "longitudinal days", the first centred on the meridian of Rome.
He also proposed a universal time to be used in astronomy and telegraphy. But his book attracted no attention until long after his death. Scottish-born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in He advocated his system at several international conferences, and is credited with "the initial effort that led to the adoption of the present time meridians".
In he specified that his universal day would begin at the anti-meridian of Greenwich th meridianwhile conceding that hourly time zones might have some limited local use. He also proposed his system at the International Meridian Conference in Octoberbut it did not adopt his time zones because they were not within its purview. The conference did adopt a universal day of 24 hours beginning at Greenwich midnight, but specified that it "shall not interfere with the use of local or standard time where desirable".
By aboutalmost all time on Earth was in the form of standard time zones, only some of which used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT.
Bymost major countries had adopted hourly time zones. Today, all nations and standard time zones for secular and, but they do not all apply the concept as originally conceived. NewfoundlandIndia, Iran, Afghanistan, Myanmar, Sri Lanka, the Marquesasas well as parts of Australia use half-hour deviations from standard time, and some and, such as Nepal, and some provinces, such as the Chatham Islands of New Zealand, use quarter-hour deviations.
Then-President And Medvedev said at the time that he would like to see even fewer in place. ISO is an international standard that defines methods of time dates and times in textual form, including specifications for representing time zones.
UTC time is also known as "Zulu" time, since "Zulu" is a phonetic alphabet code word time the letter "Z". This numeric representation of time zones is appended to local times in the same way that alphabetic time zone abbreviations or "Z", as above are appended. The offset from UTC changes with daylight saving timee. Time zones are often represented by alphabetic abbreviations such as "EST", "WST", and "CST", but these are not part of the international time and date standard ISO and their use time sole designator for a time zone is discouraged.
These examples give the local time at various locations and the world when daylight saving time is not in effect:. Howland Island.
Where the adjustment for time zones results in a time at the other side of midnight from UTC, then the date at the location time one day later or earlier. The time-zone adjustment for a specific location may vary because of daylight saving time.
The more familiar term "UTC offset" is used here rather than the term "zone designator" used by the standard.
These calculations become more complicated near a daylight saving boundary because the UTC offset for zone X is a function of the UTC time. Since the s a nautical standard time system has been in operation and ships on the high seas.
Nautical time zones are an ideal form of the terrestrial time zone system. A nautical date line is implied but not explicitly drawn on time zone maps. It follows the th meridian except where it is interrupted by territorial waters adjacent to land, forming gaps: it is a pole-to-pole dashed line. A ship within the territorial waters of any nation would use that nation's standard time, but would revert to nautical standard time upon leaving its territorial waters.
The captain is permitted to change the ship's clocks at a time of the date choice following the ship's entry into another time zone. The captain often chooses midnight. Ships going in shuttle traffic over a time zone border often keep the same time zone all the time, to avoid confusion about time, meal, and shop opening hours. Still the time table for port calls must follow the land time zone. Ideal time zones, such as nautical time zones, are based on the mean solar time of a particular meridian located in the middle of that zone with boundaries located and.
In practice, zone boundaries are often drawn much farther to the west with often irregular boundaries, and some locations base their time on meridians located far to the east. They were obliged to follow German time during the war, and kept it thereafter. In date mid s the Netherlands, as with other European states, began observing daylight saving summer time.
In the Northern hemisphere, there is a tendency to draw time zone boundaries far to the west of their meridians. A reason is that it can allow the more efficient use of sunlight.
To make solar noon coincide more with awake time noon i. This westernmost area of continental Spain never experiences sunset before clock time, even in midwinter, despite its lying more than 40 degrees north of the equator. Stockholm has much international sunrises, though. Many countries, and sometimes time certain regions of countries, adopt daylight saving time also known as "Summer Time" during part of the year.
This typically involves advancing clocks by an hour near the start of spring and adjusting back in autumn "spring forward", "fall time.
Modern DST was first proposed in and was in international use in as a wartime measure aimed at conserving coal. Despite controversy international, many countries have used it off and on since then; details vary by location and change occasionally. Most countries around the equator do not observe daylight saving time, since the seasonal difference in sunlight is minimal. Many computer operating systems include the necessary support for working with all or almost all possible local times based on the various time zones.
Internally, operating systems typically use UTC as their basic time-keeping standardwhile providing services for converting local times to and from UTC, and also the ability to automatically change local time conversions at the start and end of daylight saving time in the various time zones.
See the article on daylight saving time for more details on this aspect. Web servers presenting web pages primarily for an audience in a single time zone or a limited range of time zones typically show times as a local time, perhaps with UTC time in brackets. More internationally oriented websites may show times in UTC only or using an arbitrary time zone.
The format is typically based in the W3C Note "datetime". Email systems and other messaging systems IRC chatetc. Database records that include a time stamp typically use UTC, especially when the database is part of a system that spans multiple time zones. The use of local time for time-stamping records is not recommended for time zones that implement daylight saving time because once a year there is a one-hour period when local times are ambiguous. Calendar systems nowadays usually tie their time stamps to UTC, and show them differently on computers international are in different time zones.
That works when having telephone or internet meetings. It works date well when travelling, because the calendar events are assumed to take place in the time zone the computer or smartphone was on when creating the event. The event can be shown at the wrong time. For example, if a New Yorker plans to meet someone in Los Angeles at 9 AM, and makes a calendar entry at 9 AM which the computer assumes is New York timethe calendar entry will be at 6 International if taking the computer's time zone.
There is also an option in newer versions of Microsoft And to enter the time zone in which an event will happen, but often not in other calendar systems. Calendaring software must also deal with daylight saving time DST.
Many countries have more than one time zone. In the U. These time zones encompass most of the contiguous United States. Many countries or regions, especially those in Europe and North America practice daylight saving time DST , sometimes referred to as "summer time," with the intent of saving energy. This typically involves advancing the time on a clock by one hour in early spring, and "rolling back" the time in autumn.
Manipulating the time as the seasons change can better synchronize working hours with sunrise and sunset times in certain areas. This is less relevant for higher altitude areas where sunrise and sunset times are significantly offset with regular working hours regardless of time manipulation as well as locations near the equator since there is small variation in daylight throughout the year.
From Wikipedia, the free encyclopedia. This article is about time zones in general. For a list of time zones by country, see List of time zones by country.
For more time zone lists, see Lists of time zones. For other uses, see Time zone disambiguation. This article has multiple issues. Please help improve it or discuss these issues on the talk page. Learn how and when to remove these template messages. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. This article possibly contains original research.
Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. August Learn how and when to remove this template message. Region on Earth that has a uniform standard time for legal, commercial, and social purposes. Main article: ISO Main article: List of time zone abbreviations. Main article: List of UTC time offsets. Main article: Nautical time. DST observed. DST formerly observed.
DST never observed. Main article: Daylight saving time. This section needs additional citations for verification. Main article: Unix time. History of Mechanism and Machine Science.
Archived from the original on June 28, Retrieved December 5, How we got it. New Zealand's Method. A Lead to the World". Evening Post. Retrieved October 2, Retrieved July 30, Archived from the original PDF on May 14, Archived from the original on October 5, Retrieved February 13, October, Protocols of the proceedings. Nepali Times. Retrieved August 22, The Atlantic. March 22, Retrieved February 12, Atlas Obscura. June 8, American Practical Navigator. Washington: Government Printing Office, , , Utegaard, Gerard Riordan.
Dutton's Navigation and Piloting. Annapolis: United States Naval Institute, Greenwich Time and the Discovery of the Longitude. Oxford: Oxford University Press, Retrieved January 11, Archived from the original on November 14, Far North Science. Retrieved May 11, Canonical Ltd. August 6, Microsoft Google Calendar Help as of Oct. The Open Group. Retrieved January 22, December 26, Archived from the original on June 23, ECMA International. June Retrieved September 4, Retrieved April 14, Past history deep time Present Future Futures studies Far future in religion Far future in science fiction and popular culture Timeline of the far future Eternity Eternity of the world.
Horology History of timekeeping devices Main types astrarium atomic quantum hourglass marine sundial sundial markup schema watch mechanical stopwatch water-based Cuckoo clock Digital clock Grandfather clock. Chronology History. Religion Mythology. Geological time age chron eon epoch era period Geochronology Geological history of Earth.
Chronological dating Chronobiology Circadian rhythms Dating methodologies in archaeology Time geography. Time measurement and standards. Chronometry Orders of magnitude Metrology. Ephemeris time Greenwich Mean Time Prime meridian. Absolute space and time Spacetime Chronon Continuous signal Coordinate time Cosmological decade Discrete time and continuous time Planck time Proper time Theory of relativity Time dilation Gravitational time dilation Time domain Time translation symmetry T-symmetry.
Chronological dating Geologic time scale International Commission on Stratigraphy. Galactic year Nuclear timescale Precession Sidereal time. Authority control GND : Categories : Time zones. In many locations these offsets vary twice yearly due to DST transitions.
A timezone is a region on Earth, more or less bounded by lines of longitude, that has a uniform, legally mandated standard time, usually referred to as the localtime. By convention, the 24 main timezones on Earth compute their localtime as an offset from UTC, each timezone boundary being ostensibly 15 degrees east or west of the preceding one.
Localtime is UTC plus the current timezone offset for the location in question. DST also known as "summer time" is the practice of temporarily advancing clocks so that afternoons have more daylight and mornings have less.
Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn. In a typical case where a one-hour shift occurs at localtime, in spring the clock jumps forward from standard time to DST and that day has 23 hours, whereas in autumn the clock jumps backward from DST to standard time, repeating that hour, and that day has 25 hours. A digital display of local time does not read exactly at the shift, but instead jumps from