Date and time representation by country

Different conventions exist around the world for date and time representation, both written and spoken.

These standard notations have been adopted by many countries as a national standard, e.g., BS EN 28601 in the UK and similarly in other EU countries, ANSI INCITS 30-1997 (R2008), and FIPS PUB 4–2 in the United States (FIPS PUB 4-2 withdrawn in United States).

Some regions utilize 24-hour time notation in casual speech as well, such as regions that speak German, French, or Romanian, though this is less common overall; other countries that utilize the 24-hour clock for displaying time physically may use the 12-hour clock more often in verbal communication.

[citation needed] In most English-speaking regions, the 12-hour clock is the predominant form of representing the time of day physically, while the 24-hour clock is generally used for contexts where unambiguity and accurate timekeeping are important, such as for public transport schedules.

[citation needed] Most people who live in countries that use one of the clocks dominantly are still able to understand both systems without much confusion; the statements "three o'clock" and "15:00", for example, are easily recognized as synonyms.

[citation needed] In most countries there are no formal abbreviations to distinguish before and after noon, many people will commonly use informal designations, such as "in the morning" or "in the evening".