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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.
Time zone abbreviations for both Standard Time and Daylight Saving Time are shown exactly as they appear in the database. See strftime and its "%Z" field. Some of zone records use 3 or 4 letter abbreviations that are tied to physical time zones, others use numeric UTC offsets. List [ edit] See also [ edit] tz database.
- Etymology
- Uses
- Mechanism
- History
- Rationale
- Future
- See Also
- External Links
The official abbreviation for Coordinated Universal Time is UTC. This abbreviation comes as a result of the International Telecommunication Union and the International Astronomical Union wanting to use the same abbreviation in all languages. The compromise that emerged was UTC,which conforms to the pattern for the abbreviations of the variants of U...
Time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset. The westernmost time zone uses UTC−12, being twelve hours behind UTC; the easternmost time zone uses UTC+14, being fourteen hours ahead of UTC. In 1995, the island nation of Kiribati moved those of its atolls in the Lin...
UTC divides time into days, hours, minutes, and seconds. Days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes. The number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead. Thus, in the...
In 1928, the term Universal Time (UT) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight. Until the 1950s, broadcast time signalswere based on UT, and hence on the rotation of the Earth. In 1955, the caesium atomic clock was invented. This provided a form of timekeeping that was both more stabl...
Earth's rotational speed is very slowly decreasing because of tidal deceleration; this increases the length of the mean solar day. The length of the SI second was calibrated on the basis of the second of ephemeris time and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by Simon Newcomb. As a ...
As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. The long-term rate of change of LOD is approximately +1.7 ms per century. At the end of the 21st century, LOD will be roughly 86,400.004 s, requiring leap seconds every 250 days. Over several centuries, the frequency of leap seconds will become proble...
CurrentUTC timeW3C Specification about UTC Date and Time and RFC 3339, based on ISO 8601Daylight 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.
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. [1] .
The Global Positioning System ( GPS ), originally Navstar GPS, [2] is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. [3] .
Google LLC ( / ˈɡuːɡəl / ⓘ, GOO-ghəl) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial intelligence (AI). [9] .
