A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
Daylight saving time (DST), also referred to as daylight saving(s), daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the longer daylight available during summer, so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in spring or late winter, and to set clocks back by one hour to standard time in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").
The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States, Mexico, Central America and some Caribbean islands.
The Hawaii–Aleutian Time Zone observes Hawaii–Aleutian Standard Time (HST) by subtracting ten hours from Coordinated Universal Time (UTC−10:00). The clock time in this zone is based on the mean solar time of the 150th meridian west of the Greenwich Observatory.
Summer time in Europe is the variation of standard clock time that is applied in most European countries in the period between spring and autumn, during which clocks are advanced by one hour from the time observed in the rest of the year, with a view to making the most efficient use of seasonal daylight. It corresponds to the notion and practice of daylight saving time (DST) to be found in some other parts of the world.
There are eleven time zones in Russia, which currently observe times ranging from UTC+02:00 to UTC+12:00. Daylight saving time (DST) has not been used in Russia since 26 October 2014. From 27 March 2011 to 26 October 2014, permanent DST was used.
Time in Chile is divided into three time zones. Most of Continental Chile uses the time offset UTC−04:00 in winter time and UTC−03:00 in summer time, while the Magallanes and Chilean Antarctica region uses the time offset UTC−03:00 the whole year. Additionally, Easter Island uses the time offset UTC−06:00 in winter time and UTC−05:00 in summer time.
Iran Standard Time (IRST) or Iran Time (IT) is the time zone used in Iran. Iran uses a UTC offset UTC+03:30. IRST is defined by the 52.5 degrees east meridian, the same meridian which defines the Iranian calendar and is the official meridian of Iran.
Most of the United States observes daylight saving time, the practice of setting the clock forward by one hour when there is longer daylight during the day, so that evenings have more daylight and mornings have less. Exceptions include Arizona, Hawaii, and the territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Uniform Time Act of 1966 established the system of uniform daylight saving time throughout the US.
Samoa uses UTC+13:00 as standard time. Until the end of 2011, it used UTC−11:00 as standard time. Samoa observed daylight saving time from 2010 to 2021.
Brazil observed daylight saving time (DST) in the years of 1931–1933, 1949–1953, 1963–1968 and 1985–2019. Initially it applied to the whole country, but from 1988 it applied only to part of the country, usually the southern regions, where DST is more useful due to a larger seasonal variation in daylight duration.
Pakistan has experimented with Daylight Saving Time (DST) a number of times since 2002, shifting local time from UTC+05:00 to UTC+06:00 during various summer periods.
Daylight saving time in the Americas is the arrangement in the Americas by which clocks are advanced by one hour in spring and moved back in autumn, to make the most of seasonal daylight. The practice is widespread in North America, with most of Canada and the United States participating, but much less so in Central and South America.
As of 2018, daylight saving time (DST) is permanently observed in Morocco. Previously, time was advanced to UTC+01:00 at 02:00 on the last Sunday of March, and reverted to UTC±00:00, defined as Greenwich Mean Time locally, at 03:00 on the last Sunday of October. This practice was continued until October 2018, after which clocks were permanently advanced. An exception was made during the month of Ramadan during which clocks reverted to UTC+00:00.
Daylight saving time in Iran was the practice of setting the clock forward by one hour between the first day of Farvardin in the Iranian calendar and the last day of Shahrivar, which has been observed during years 1978–1980, 1989–2005, and 2008–2022.
Samoa observed daylight saving time in 2010–21. During DST, the observed time changes were from UTC+13:00 to UTC+14:00. Due to the 2009 Samoa tsunami, the planned introduction in 2009 was not carried out. At the time of its introduction on September 26, Samoa was in UTC-11:00 as its primary time zone and switched to UTC-10:00 under DST. On December 29, 2011, Samoa switched from UTC-10:00 to UTC+14:00, skipping the 30th and changing from -10/-11 to +14/+13. In 2021 Samoa scrapped daylight saving time.
As of 2022, daylight saving time is used in the following Asian countries:
Parts of Australia, New Zealand and Fiji are areas of Oceania that currently observe daylight saving time (DST).
Daylight saving time (DST), also known as summer time, is the practice of advancing clocks during part of the year, typically by one hour around spring and summer, so that daylight ends at a later time of the day. As of 2024, DST is observed in most of Europe, most of North America and parts of Africa and Asia around the Northern Hemisphere summer, and in parts of South America and Oceania around the Southern Hemisphere summer. It was also formerly observed in other areas.
Time in Fiji is given by Fiji Time (FJT) (UTC+12:00), as standard time, and UTC+13:00 as daylight saving time. Fiji decides year by year whether it will observe DST, and if so for which dates, which are usually a short period between November or December and January. No DST has been observed since 2020-2021.
