ISO 8601 in the context of "24-hour clock"

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⭐ Core Definition: ISO 8601

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.

ISO 8601 applies to these representations and formats: dates, in the Gregorian calendar (including the proleptic Gregorian calendar); times, based on the 24-hour timekeeping system, with optional UTC offset; time intervals; and combinations thereof. The standard does not assign specific meaning to any element of the dates/times represented: the meaning of any element depends on the context of its use. Dates and times represented cannot use words that do not have a specified numerical meaning within the standard (thus excluding names of years in the Chinese calendar), or that do not use computer characters (excludes images or sounds).

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👉 ISO 8601 in the context of 24-hour clock

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 00(:00) to 23(:59), with 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, and is used by the international standard ISO 8601.

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.

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ISO 8601 in the context of Year zero

A year zero does not exist in the Anno Domini (AD) calendar year system commonly used to number years in the Gregorian calendar (or in its predecessor, the Julian calendar); in this system, the year 1 BC is followed directly by year AD 1 (which is the year of the epoch of the era). However, there is a year zero in both the astronomical year numbering system (where it coincides with the Julian year 1 BC), and the ISO 8601:2004 system, a data interchange standard for certain time and calendar information (where year zero coincides with the Gregorian year 1 BC; see: Holocene calendar § Conversion). There is also a year zero in most Buddhist and Hindu calendars.

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ISO 8601 in the context of Sunday

Sunday (Latin: dies solis meaning "day of the sun") is the day of the week between Saturday and Monday. Sunday is a day of rest in most Western countries and a part of the weekend. In some Middle Eastern countries, Sunday is a weekday.

For most Christians, Sunday is observed as a day of worship and rest, holding it as the Lord's Day and the day of Christ's resurrection; in the United States, Canada, Japan, as well as in parts of South America, Sunday is the first day of the week. According to the Islamic calendar, Hebrew calendar and traditional calendars (including Christian calendars) Sunday is the first day of the week; Quaker Christians call Sunday the "first day" in accordance with their testimony of simplicity. The International Organization for Standardization ISO 8601, which is based in Switzerland, calls Sunday the seventh day of the week.

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ISO 8601 in the context of Tuesday

Tuesday is the day of the week between Monday and Wednesday. According to international standard ISO 8601, Monday is the first day of the week; thus, Tuesday is the second day of the week. According to many traditional calendars, however, Sunday is the first day of the week, so Tuesday is the third day of the week. In some Muslim countries, Saturday is the first day of the week and thus Tuesday is the fourth day of the week.

The English name is derived from Middle English Tewesday, from Old English Tiwesdæg meaning "Tīw's Day", the day of Tiw or Týr, the god of single combat, law, and justice in Norse mythology. Tiw was equated with Mars in the interpretatio germanica, and the name of the day is a translation of Latin dies Martis.

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ISO 8601 in the context of ISO week date

The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2019) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.

The Gregorian leap cycle, which has 97 leap days spread across 400 years, contains a whole number of weeks (20871). In every cycle there are 71 years with an additional 53rd week (corresponding to the Gregorian years that contain 53 Thursdays). An average year is exactly 52.1775 weeks long; months (1⁄12 year) average at exactly 4.348125 weeks/month.

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LINKED FROM (PARENTS)
← Year zero ← Sunday ← Tuesday ← ISO week date ← 24-hour clock
LINKS TO (CHILDREN)
International standard → Time → International Organization for Standardization → Date and time representation by country → Gregorian calendar → Proleptic Gregorian calendar → 24-hour clock → UTC offset → Time interval → Chinese calendar correspondence table → Chinese calendar → Character (computing) →