You have to think global these days. – @etherealmind
Most countries use the day / month / year, but a few countries use month / day / year. This causes major problems in documentation (at least) when one group is referring to 1/2 (1st February) and the other group 2/1 (2nd January).
My personal fix for this has been to use year / month / day. But my main reason has been to organise files in date order and get useful directory listing.
I recently discovered that there is an ISO standard for laying out dates in exactly this manner. ISO8601 was published in 1988, and updated in 2004 and is available ISO8601 at Wikipedia.
Calendar date is the most common date representation. It is:
where YYYY is the year in the Gregorian calendar, MM is the month of the year between 01 (January) and 12 (December), and DD is the day of the month between 01 and 31.
Example: 2003-04-01 represents the first day of April in 2003.
Time of Day
Time of the day is the time representation, using the 24-hour timekeeping system. It is:
where hh is the number of complete hours that have passed since midnight, mm is the number of complete minutes since the start of the hour, and ss is the number of complete seconds since the start of the minute.
Example: 23:59:59 represents the time one second before midnight.
Date and Time
Date and time represents a specified time of a specified day. When use is made of the calendar date the representation is:
where the capital letter T is used to separate the date and time components. Thus, for a very precise date and time, look at this:
Example: 2003-04-01T13:01:02 represents one minute and two seconds after one o’clock in the afternoon of 2003-04-01.
If you are writing documents that you are going to send to a Global Audience, this is a good standard to use. Because the YEAR is the first number, it is immediately obvious that the date format is different to what you were taught at school, and it is obvious what the format means.
I would like to see everyone adopt this standard, and make my life simpler. It seems every other week I have a fellow worker in the USA who gets the date mixed up because they use different format by default. ISO 8601 means that both parties have to change and this works well in terms of gaining acceptance.
I hope you think so too.
Note that you should only use the format YYYY / MM / DD to ensure Y3K or turn of the century problems.