Editing Clock (section)

{{Short description|Instrument for measuring, keeping or indicating time}}
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{{redirect|Timepiece|other uses|Clock (disambiguation)|and|Timepiece (disambiguation)}}
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[[File:Pendulum clock by Jacob Kock, antique furniture photography, IMG 0931 edit.jpg|thumb|An analog [[pendulum clock]] made around 18th century]]

A '''clock''' or '''chronometer'''<!--not timepiece--> is a device that measures and displays [[time]]. The clock is one of the oldest [[Invention|human inventions]], meeting the need to measure intervals of time shorter than the natural units such as the [[day]], the [[lunar month]], and the<!-- Per WP:RETAIN and MOS:OXFORD, please do not remove comma without consensus on the talk page --> [[year]]. Devices operating on several physical processes have been used over the [[Millennium|millennia]].

Some predecessors to the modern clock may be considered "clocks" that are based on movement in nature: A [[sundial]] shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the [[hourglass]]. [[Water clock]]s, along with sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the [[verge escapement]], which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like [[balance wheel]]s.<ref name="Dohrn">{{cite book
|last=Dohrn-van Rossum
|first=Gerhard
|title=History of the Hour: Clocks and Modern Temporal Orders
|year=1996
|publisher=Univ. of Chicago Press
|url=https://books.google.com/books?id=xYhlNoUu-toC&q=verge+escapement+technology
|isbn=978-0-226-15511-1
|access-date=October 30, 2020
|archive-date=July 3, 2023
|archive-url=https://web.archive.org/web/20230703112705/https://books.google.com/books?id=xYhlNoUu-toC&q=verge+escapement+technology
|url-status=live
}}, pp. 103–104.</ref><ref name="Marrison">{{cite journal|last=Marrison|first=Warren|title=The Evolution of the Quartz Crystal Clock|journal=Bell System Technical Journal|year=1948|volume=27|issue=3|pages=510–588|url=http://timepieceperfection.com/THE-BELL-SYSTEM.pdf|access-date=10 November 2014|doi=10.1002/j.1538-7305.1948.tb01343.x|archive-url=https://web.archive.org/web/20141110143908/http://timepieceperfection.com/THE-BELL-SYSTEM.pdf|archive-date=November 10, 2014 | issn = 0005-8580 }}</ref><ref name="Cipolla">{{cite book|last=Cipolla|first=Carlo M.|title=Clocks and Culture, 1300 to 1700|year=2004|publisher=W.W. Norton & Co.|isbn=978-0-393-32443-3|url=https://books.google.com/books?id=YSf9MVxa2JEC&q=verge+escapement+technology&pg=PA31|access-date=October 30, 2020|archive-date=July 3, 2023|archive-url=https://web.archive.org/web/20230703112708/https://books.google.com/books?id=YSf9MVxa2JEC&q=verge+escapement+technology&pg=PA31|url-status=live}}, p. 31.</ref><ref name="White">{{cite book
 | last = White
 | first = Lynn Jr.
 | title = Medieval Technology and Social Change
 | publisher = Oxford Univ. Press
 | year = 1962
 | location = UK
 | page = 119
 }}</ref>

Traditionally, in [[horology]] (the study of timekeeping), the term ''clock'' was used for a [[striking clock]], while a clock that did not strike the hours audibly was called a '''timepiece'''. This distinction is not generally made any longer. [[Watch]]es and other timepieces that can be carried on one's person are usually not referred to as clocks.<ref>{{cite web |title=Cambridge Advanced Learner's Dictionary |url=https://dictionary.cambridge.org/dictionary/english/clock |access-date=2018-01-29 |quote=a device for measuring and showing time, which is usually found in or on a building and is not worn by a person |archive-date=March 7, 2023 |archive-url=https://web.archive.org/web/20230307021636/https://dictionary.cambridge.org/dictionary/english/clock |url-status=live }}</ref> Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, [[clockmaking]] flourished. The next development in accuracy occurred after 1656 with the invention of the [[pendulum clock]] by [[Christiaan Huygens]]. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The mechanism of a timepiece with a series of gears driven by a spring or weights is referred to as [[clockwork]]; the term is used by extension for a similar mechanism not used in a timepiece. The [[electric clock]] was patented in 1840, and electronic clocks were introduced in the 20th century, becoming widespread with the development of small battery-powered [[semiconductor device]]s.

The timekeeping element in every modern clock is a [[harmonic oscillator]], a physical object ([[resonator]]) that vibrates or oscillates at a particular frequency.<ref name="Marrison" />
This object can be a [[pendulum]], a [[balance wheel]], a [[tuning fork]], a [[crystal oscillator|quartz crystal]], or the vibration of [[electron]]s in [[atom]]s as they emit [[microwave]]s, the last of which is so precise that it serves as the formal definition of the [[second]].

[[File:Casio F-91W 82T38575.jpg|thumb|[[Casio F-91W]] [[digital clock|digital watch]], a historically popular watch introduced in 1989]]
Clocks have different ways of displaying the time. Analog clocks indicate time with a traditional [[clock face]] and moving hands. Digital clocks display a numeric representation of time. Two numbering systems are in use: [[12-hour time]] notation and [[24-hour clock|24-hour]] notation. Most digital clocks use electronic mechanisms and [[LCD]], [[LED]], or [[Vacuum fluorescent display|VFD]] displays. For the blind and for use over telephones, [[speaking clock]]s state the time audibly in words. There are also clocks for the blind that have displays that can be read by touch.