Editing 24-hour clock (section)

{{Short description|Timekeeping convention}}
{{Use dmy dates|date=January 2024}}
{{Use British English|date=July 2023|cs1-dates=ll}}

The modern '''24-hour clock''' is the convention of [[timekeeping]] in which the [[day]] runs from [[midnight]] to midnight and is divided into 24 hours. This is indicated by the hours (and minutes) passed since midnight, from {{Nowrap|00(:00)}} to {{Nowrap|23(:59)}}, with {{Nowrap|24(:00)}} as an option to indicate the end of the day. This system, as opposed to the [[12-hour clock]], is the most commonly used time notation in the world today,{{Efn-ua|name=CLDR|See the [[Common Locale Data Repository]] for detailed data about the preferred date and time notations used across the world, as well the [[Locale (computer software)|locale]] settings of major computer [[operating system]]s, and the article [[Date and time representation by country]].}} and is used by the international standard [[ISO 8601]].<ref name="iso8601">{{cite ISO standard |title=ISO 8601-1:2019 – Date and time — Representations for information interchange |csnumber=70907 |edition=1st |date=2019}}</ref>

A number of countries, particularly English speaking, use the 12-hour clock, or a mixture of the 24- and 12-hour time systems. In countries where the 12-hour clock is dominant, some professions prefer to use the 24-hour clock. For example, in the practice of [[medicine]], the 24-hour clock is generally used in documentation of care as it prevents any [[ambiguity]] as to when events occurred in a patient's [[medical history]].<ref>{{Cite book |title=Dosage calculations |last1=Pickar |first1=Gloria D. |last2=Graham |first2=Hope |last3=Swart |first3=Beth |last4=Swedish |first4=Margaret |date=2011 |publisher=Nelson Education |isbn=9780176502591 |edition=2nd Canadian |location=Toronto |page=60}}</ref>