Editing Red (section)

=== Warning and danger ===
Red is the traditional color of warning and danger, and is therefore often used on flags. In the Middle Ages up through the [[French Revolution]], a [[Red flag (signal)|red flag]] shown in warfare indicated the intent to take no prisoners.<ref>{{Cite book|url=https://books.google.com/books?id=CNB0DwAAQBAJ&q=%22red+flag%22+%22middle+ages%22+siege&pg=PA11|title=Renaissance Mass Murder: Civilians and Soldiers During the Italian Wars|last=Bowd|first=Stephen D.|date=2019-01-22|publisher=Oxford University Press|isbn=9780198832614|language=en|access-date=2020-10-16|archive-date=2020-11-01|archive-url=https://web.archive.org/web/20201101102146/https://books.google.com/books?id=CNB0DwAAQBAJ&q=%22red+flag%22+%22middle+ages%22+siege&pg=PA11|url-status=live}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=kE0C5TFnN5IC&q=%22red+flag%22+%22middle+ages%22+siege&pg=RA1-PA106|title=Naval War College Review|date=1993|publisher=Naval War College|language=en|access-date=2020-10-16|archive-date=2020-11-01|archive-url=https://web.archive.org/web/20201101102157/https://books.google.com/books?id=kE0C5TFnN5IC&q=%22red+flag%22+%22middle+ages%22+siege&pg=RA1-PA106|url-status=live}}</ref> Similarly, a red flag hoisted by a [[pirate ship]] meant no mercy would be shown to their target.<ref>{{Cite book|url=https://books.google.com/books?id=28d0Pap9l2wC&q=%22red+flag%22+mercy|title=Honor Among Thieves: Captain Kidd, Henry Every, and the Story of Pirate Island|last=Rogoziński|first=Jan|date=2001-04-01|publisher=Conway|isbn=9780851777924|language=en|access-date=2020-10-16|archive-date=2020-11-01|archive-url=https://web.archive.org/web/20201101102147/https://books.google.com/books?id=28d0Pap9l2wC&q=%22red+flag%22+mercy|url-status=live}}</ref><ref>Cordingly, p. 117.  Cordingly cites only one source for pages 116–119 of his text: ''Calendar of State Papers, Colonial, America and West Indies'', volumes 1719–20, no. 34.</ref> In Britain, in the early days of motoring, motor cars had to follow a man with a red flag who would warn horse-drawn vehicles, before the [[Locomotives on Highways Act 1896]] abolished this law.<ref>{{Cite book|url=https://books.google.com/books?id=rzIlDwAAQBAJ&q=%22Locomotives+on+Highways+Act+1896%22+flag&pg=PA92|title=Automobile Heritage and Tourism|last1=Conlin|first1=Michael V.|last2=Jolliffe|first2=Lee|date=December 2016|publisher=Taylor & Francis|isbn=9781315436203|language=en|access-date=2020-10-16|archive-date=2020-11-01|archive-url=https://web.archive.org/web/20201101102147/https://books.google.com/books?id=rzIlDwAAQBAJ&q=%22Locomotives+on+Highways+Act+1896%22+flag&pg=PA92|url-status=live}}</ref> In automobile races, the red flag is raised if there is danger to the drivers.<ref>{{Cite web|url=http://news.bbc.co.uk/sport2/hi/motorsport/formula_one/flags_guide/default.stm#targetText=The%20race%20has%20been%20stopped,for%20racing%20to%20be%20safe.&targetText=Indicates%20danger%20ahead%20and%20overtaking%20is%20prohibited.|title=BBC SPORT {{!}} Motorsport {{!}} Formula One {{!}} Flags guide|website=news.bbc.co.uk|access-date=2019-10-08|archive-date=2019-11-02|archive-url=https://web.archive.org/web/20191102034845/http://news.bbc.co.uk/sport2/hi/motorsport/formula_one/flags_guide/default.stm#targetText=The%20race%20has%20been%20stopped,for%20racing%20to%20be%20safe.&targetText=Indicates%20danger%20ahead%20and%20overtaking%20is%20prohibited.|url-status=live}}</ref> In international football, a player who has made a serious violation of the rules is shown a red [[penalty card]] and ejected from the game.<ref>{{cite web|url=https://digitalhub.fifa.com/m/3f3e15cc1ab8977b/original/datdz0pms85gbnqy4j3k-pdf.pdf|title=Laws of The Game|website=fifa.com|publisher=Fédération Internationale de Football Association|pages=39, 72, 82–83|archive-url=https://web.archive.org/web/20180311174803/https://img.fifa.com/image/upload/datdz0pms85gbnqy4j3k.pdf|archive-date=March 11, 2018|url-status=live|access-date=Mar 11, 2018}}</ref>

Several studies have indicated that red carries the strongest reaction of all the colors, with the level of reaction decreasing gradually with the colors orange, yellow, and white, respectively.<ref>{{Cite book|title=Contemporary ergonomics 1996|date=1996|publisher=Taylor & Francis|isbn=978-0748405497|editor-last=Robertson|editor-first=S. A.|location=London|pages=148–50|oclc=34731604}}</ref><ref>{{Cite book|title=International encyclopedia of ergonomics and human factors|last=Karwowski|first=Waldemar|date=2006|publisher=CRC|isbn=978-0415304306|edition=2nd|location=Boca Raton|pages=1518|oclc=251383265}}</ref> For this reason, red is generally used as the highest level of warning, such as threat level of terrorist attack in the United States. In fact, teachers at a primary school in the UK have been told not to mark children's work in [[red ink]] because it encourages a "negative approach".<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/education/2688623.stm|title=Red ink banned from primary books|date=Jan 23, 2003|work=BBC News World Edition|access-date=Aug 15, 2013|archive-url=https://web.archive.org/web/20170730024918/http://news.bbc.co.uk/1/hi/education/2688623.stm|archive-date=July 30, 2017|url-status=live}}</ref>

Red is the international color of stop signs and stop lights on highways and intersections. It was standardized as the international color at the [[Vienna Convention on Road Signs and Signals]] of 1968. It was chosen partly because red is the brightest color in daytime (next to orange), though it is less visible at twilight, when green is the most visible color. Red also stands out more clearly against a cool natural backdrop of blue sky, green trees or gray buildings. But it was mostly chosen as the color for stoplights and stop signs because of its universal association with danger and warning.<ref name=":1" />{{Rp|54}} The 1968 [[Vienna Convention on Road Signs and Signals]] of 1968 uses red color also for the margin of danger warning sign, give way signs and prohibitory signs, following the previous German-type signage (established by Verordnung über Warnungstafeln für den Kraftfahrzeugverkehr in 1927).

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Vienna Convention road sign B2a.svg|The standard international stop sign, following the [[Vienna Convention on Road Signs and Signals]] of 1968
File:SM-PAOK (18).jpg|A footballer is shown a red card and ejected from a soccer match.
Red typhoon alert.png|A red Chinese typhoon alert sign
Hsas-chart with header.svg|Red is the color of a severe terrorist threat level in the United States, under the [[Homeland Security Advisory System]].
AU Fire Danger Indicator.jpg|Red is the color of extreme fire danger in Australia; new black/red stripes are an even more catastrophic hazard.
</gallery>