ISO 8601 is an international standard covering the worldwide exchange and communication of date and time-related data. It is maintained by the International Organization for Standardization (ISO) and was first published in 1988, with updates in 1991, 2000, 2004, and 2019, and an amendment in 2022. The standard provides a well-defined, unambiguous method of representing calendar dates and times in worldwide communications, especially to avoid misinterpreting numeric dates and times when such data is transferred between countries with different conventions for writing numeric dates and times.
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.
Central European Time (CET) is a standard time of Central, and parts of Western Europe, which is one hour ahead of Coordinated Universal Time (UTC). The time offset from UTC can be written as UTC+01:00. It is used in most parts of Europe and in a few North African countries. CET is also known as Middle European Time and by colloquial names such as Amsterdam Time, Berlin Time, Brussels Time, Budapest Time,Madrid Time, Paris Time, Rome Time,Prague time,Warsaw Time or Romance Standard Time (RST).
Western European Time is a time zone covering parts of western Europe and consists of countries using UTC±00:00. It is one of the three standard time zones in the European Union along with Central European Time and Eastern European Time.
Singapore Time (SGT), also known as Singapore Standard Time (SST), is used in Singapore and is 8 hours ahead of UTC (UTC+08:00). Singapore does not observe daylight saving time.
UTC+5:30 is an identifier for a time offset from UTC of +05:30. This time is used in India and Sri Lanka, and was formerly used in Nepal. It is five and a half hours ahead of Coordinated Universal Time. Around 1.4 billion people live inside this time zone, making it the second-most populous after UTC+08:00.
UTC+02:00 is an identifier for a time offset from UTC of +02:00. In ISO 8601, the associated time would be written as 2020-11-08T23:41:45+02:00. This time is used in:
UTC+03:00 is an identifier for a time offset from UTC of +03:00. In areas using this time offset, the time is three hours later than the Coordinated Universal Time (UTC). Following the ISO 8601 standard, a time with this offset would be written as, for example, 2019-02-08T23:36:06+03:00.
UTC+05:45 is an identifier for a time offset from UTC of +05:45. The time zone is used in Nepal. It is one of only three time zones with a 45-minute offset from UTC.
The Chatham Standard Time Zone is a time zone twelve hours and forty-five minutes ahead of Coordinated Universal Time (UTC) resulting in UTC+12:45. It is used exclusively in the Chatham Islands, New Zealand. It is one of three time zones with a 45-minute offset from UTC, the others being Nepal Standard Time (UTC+05:45) and the unofficial Australian Central Western Time (UTC+08:45).
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.
Thailand follows UTC+07:00, which is 7 hours ahead of UTC. The local mean time in Bangkok was originally UTC+06:42:04. Thailand used this local mean time until 1920, when it changed to Indochina Time, UTC+07:00; ICT is used all year round as Thailand never observed daylight saving time. Thailand shares the same time zone with Vietnam, Cambodia, Laos, Christmas Island, and Western Indonesia.
UTC+07:20 is an identifier for a time offset from UTC of +07:20.
UTC+05:40 is an identifier for a time offset from UTC of +05:40. It is not currently used in any region in the world, but it was formerly used in Nepal.
Philippine Standard Time, also known as Philippine Time (PHT), is the official name for the time zone used in the Philippines. The country only uses a single time zone, at an offset of UTC+08:00, but has used daylight saving time for brief periods in the 20th century until July 28, 1990.
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.
Bangladesh Standard Time is the time zone of Bangladesh. It is offset six hours ahead of Coordinated Universal Time, and observed as a national standard throughout the country. Bangladesh briefly observed daylight saving time (DST) in 2009 to cope with the ongoing electricity crisis, but in 2010 the decision was cancelled by the government of Bangladesh.
Venezuela uses the UTC−04:00 time offset, and they had previously used UTC−04:30 from 9 December 2007 until 30 April 2016. The time is commonly called Venezuelan Standard Time (VET), and legally referred to as Hora Legal de Venezuela (HLV) or Venezuela's Legal Time. The HLV is administered by the Navigation and Hydrography Service, in the Cagigal Naval Observatory, Caracas.
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.
