Daylight saving time

DSTdaylight savingPSTDaylight Savings Timesummer timeDaylight Savingsdaylight timedaylight-saving timetime changepermanent daylight saving time
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Daylight saving time by country

Daylight saving time around the worldcountries have useddaylight saving periods
Many countries have used it at various times since then, particularly since the 1970s energy crisis.
Most areas in Europe and North America observe daylight saving time (DST), while most areas of Africa and Asia do not.

Time zone

Sri Lanka Standard Time Zonetime zoneslocal time
The effect also varies according to how far east or west the location is within its time zone, with locations farther east inside the time zone benefiting more from DST than locations farther west in the same time zone.
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.

Standard time

TimeAllegheny Time SystemEST
By synchronously resetting all clocks in a region to one hour ahead of standard time, individuals who follow such a year-round schedule will wake an hour earlier than they would have otherwise; they will begin and complete daily work routines an hour earlier, and they will have available to them an extra hour of daylight after their workday activities.
In regions where daylight saving time is used, that time is defined by another offset, from the standard time in its applicable time zones.

Coordinated Universal Time

UTCUTC-3UTC-4
Members of the European Union conduct a coordinated shift, shifting all zones at the same instant, at 01:00 Coordinated Universal Time (UTC), which means that it changes at 02:00 Central European Time (CET), equivalent to 03:00 Eastern European Time (EET); as a result, the time differences across European time zones remain constant.
It is within about 1 second of mean solar time at 0° longitude, and is not adjusted for daylight saving time.

Eastern European Time

EETUTC+2UTC+02:00
Members of the European Union conduct a coordinated shift, shifting all zones at the same instant, at 01:00 Coordinated Universal Time (UTC), which means that it changes at 02:00 Central European Time (CET), equivalent to 03:00 Eastern European Time (EET); as a result, the time differences across European time zones remain constant.
The zone uses daylight saving time, so that it uses UTC+03:00 during the summer.

Mountain Time Zone

Mountain (MST)MSTMDT
North America shifts at 02:00 but at the local time and is consequently uncoordinated - so that, for example, Mountain Time is, for one hour in the autumn, zero hours ahead of Pacific Time instead of one hour ahead and, for one hour in the spring, two hours ahead of Pacific Time instead of one hour ahead.
The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time is in effect, and by subtracting six hours during daylight saving time (UTC−06:00).

Winter time (clock lag)

winter timeCzechoslovakia
The opposite is also possible, with Ireland, for example, defining its summer time to be the legal standard and winter time to be a negative offset.
It is a form of daylight saving time which is the opposite compensation to the summer time (+1, +2).

Robert Pearce (British politician)

Robert PearcePearce, RobertRobert Pearce (MP)
Liberal Party member of parliament Robert Pearce took up the proposal, introducing the first Daylight Saving Bill to the House of Commons on February 12, 1908.
He was a Member of Parliament (MP) for all but one of the years from 1906 to 1918, and was an early advocate in Parliament of daylight saving time.

Central European Time

CETUTC+1Central Europe Time
Members of the European Union conduct a coordinated shift, shifting all zones at the same instant, at 01:00 Coordinated Universal Time (UTC), which means that it changes at 02:00 Central European Time (CET), equivalent to 03:00 Eastern European Time (EET); as a result, the time differences across European time zones remain constant. In the United Kingdom, the standard term for UK time when advanced by one hour is British Summer Time (BST), and British English typically inserts summer into other time zone names, e.g. Central European Time (CET) becomes Central European Summer Time (CEST).
As of 2011, all member states of the European Union observe summer time; those that during the winter use CET use Central European Summer Time (CEST) (or: UTC+02:00, daylight saving time) in summer (from last Sunday of March to last Sunday of October).

Benjamin Franklin

Ben FranklinFranklinFranklin, Benjamin
Benjamin Franklin published the proverb "early to bed and early to rise makes a man healthy, wealthy, and wise", and he published a letter in the Journal de Paris during his time as an American envoy to France (1776–1785) suggesting that Parisians economize on candles by rising earlier to use morning sunlight.
Daylight saving time (DST) is often erroneously attributed to a 1784 satire that Franklin published anonymously.

Eastern Time Zone

Eastern (EST)ESTEDT
For example, Central European Time is usually six hours ahead of North American Eastern Time, except for a few weeks in March and October/November, while the United Kingdom and mainland Chile could be five hours apart during the northern summer, three hours during the southern summer, and four hours for a few weeks per year.
Eastern Daylight Time (EDT), when observing daylight saving time (spring/summer), is four hours behind Coordinated Universal Time (UTC−04:00).

Orillia

Orillia, OntarioGrape IslandOrillia, ON
This was followed by Orillia, Ontario, introduced by William Sword Frost while mayor from 1911 to 1912.
Orillia was the first municipality in North America to introduce daylight saving time and had the first municipal hydroelectric transmission plant in North America.

George Hudson (entomologist)

George HudsonGeorge Vernon HudsonHudson
George Hudson proposed the idea of daylight saving in 1895.
Hudson is credited with proposing modern-day daylight saving time.

Civil time

civil dayclock time
From the 14th century onwards, equal-length civil hours supplanted unequal ones, so civil time no longer varies by season.
Modern civil time is generally standard time in a time zone at a fixed offset from Coordinated Universal Time (UTC) or from Greenwich Mean Time (GMT), possibly adjusted by daylight saving time during part of the year.

Journal de Paris

Benjamin Franklin published the proverb "early to bed and early to rise makes a man healthy, wealthy, and wise", and he published a letter in the Journal de Paris during his time as an American envoy to France (1776–1785) suggesting that Parisians economize on candles by rising earlier to use morning sunlight.
In 1784, the paper famously published an anonymous satirical letter by Benjamin Franklin encouraging Parisians to rise earlier in the day, which has been credited (though an overreach) with promoting the concept of daylight saving time.

Cortes of Cádiz

Cádiz CortesCortes de CádizCortes
In 1810, the Spanish National Assembly Cortes of Cádiz issued a regulation that moved certain meeting times forward by one hour from May 1 to September 30 in recognition of seasonal changes, but it did not actually change the clocks.
Its first regulation includes one of the first proofs of steady seasonally times which came into the time change.

History of time in the United States

Daylight SavingEastern War TimeEWT
The history of time in the United States includes DST during both world wars, but no standardization of peacetime DST until 1966.
The act also established daylight saving time, itself a contentious idea.

Daylight Saving for South East Queensland

Daylight Saving for South East Queensland (DS4SEQ)DS4SEQ
In December 2008, the Daylight Saving for South East Queensland (DS4SEQ) political party was officially registered in Queensland, advocating the implementation of a dual-time zone arrangement for daylight saving in South East Queensland, while the rest of the state maintains standard time.
It was a single-issue party, run by volunteers, that advocated the introduction of Daylight Saving into Queensland, or at the very least into South East Queensland under a dual-time zone arrangement - with the remainder of the state to maintain standard time.

Time in Chile

CLTCLSTChile Standard Time
For example, mainland Chile observes DST from the second Saturday in October to the second Saturday in March, with transitions at 24:00 local time.
Until 2015, Continental Chile used the time offset UTC−04:00 and Easter Island used UTC−06:00 for standard time, with daylight saving time roughly between October and March every year.

Daylight Saving for South East Queensland Referendum Bill 2010

Daylight Saving for South East Queensland Referendum Act 2010
Queensland Independent member Peter Wellington introduced the Daylight Saving for South East Queensland Referendum Bill 2010 into the Queensland parliament on April 14, 2010, after being approached by the DS4SEQ political party, calling for a referendum at the next state election on the introduction of daylight saving into South East Queensland under a dual-time zone arrangement.
Wellington has called for a referendum to be held at the next State election on introduction of daylight saving time for South East Queensland.

Time in Australia

AESTAustralian Eastern Standard TimeAWST
In the past, Australian state jurisdictions not only changed at different local times but sometimes on different dates; for example, in 2008 most DST-observing states shifted clocks forward on October 5 but Western Australia shifted on October 26.
Daylight saving time (+1 hour) is used in states in the south and south-east—South Australia, New South Wales, Victoria, Tasmania, and the ACT.

Energy Policy Act of 2005

Energy Policy ActHalliburton loophole2005 Energy Bill
The 2007 U.S. change conformed to the Energy Policy Act of 2005; previously, from 1987 through 2006, the start- and end-dates were the first Sunday in April and the last Sunday in October.
The bill amends the Uniform Time Act of 1966 by changing the start and end dates of daylight saving time, beginning in 2007.

Central European Summer Time

CESTUTC+2EEST
In the United Kingdom, the standard term for UK time when advanced by one hour is British Summer Time (BST), and British English typically inserts summer into other time zone names, e.g. Central European Time (CET) becomes Central European Summer Time (CEST).
Central European Summer Time (CEST), sometime referred also as Central European Daylight Time (CEDT), is the standard clock time observed during the period of summer daylight-saving in those European countries which observe Central European Time (UTC+01:00) during the other part of the year.

Tz database

IANA time zone databasetime zone databaseOlson Data
Many systems in use today base their date/time calculations from data derived from the tz database also known as zoneinfo.
It also includes transitions such as daylight saving time, and also records leap seconds.

List of tz database time zones

zone.tabAsia/Dubaideprecated time zone identifier
In Unix-like systems the TZ environment variable specifies the location name, as in.
The UTC DST offset is different from the UTC offset for zones where daylight saving time is observed (see individual time zone pages for details).