That's the official one from the all numeric date... but...

https://en.wikipedia.org/wiki/Date_and_time_notation_in_Cana...

All of the following dates are valid:

3 May 2021

May 3, 2021

3 mai 2021

2021-05-03

And from https://en.wikipedia.org/wiki/Date_format_by_country

> ISO 8601 is the only format that the Government of Canada and Standards Council of Canada officially recommend for all-numeric dates.[28][29][30] But, their usage differs depending of many contexts.[31][32]

> All three formats are used in Canada for long format.

> For English speakers, MDY was preferred form (mmm-dd-yyyy) (Example: April 9, 2019) and used by nearly all English language publications and media companies as well as majority of English language government documents.[citation needed]

> For both French and sometimes English speakers, DMY are used (dd-mmm-yyyy) (Example: 9 April 2019/le 9 avril 2019) and also used in formal letters, academic papers, military, many media companies and even some governmental documents, particularly in French-language ones.

> Federal regulations for shelf life dates on perishable goods mandate a year/month/day format, but allow the month to be written in full, in both official languages, or with a set of standardized two-letter bilingual codes such as 2019 JA 07 or 19 JA 07.

Still, the one that contains only numbers (the most potentially ambiguous) is of the format yyyy-MM-dd

Apparently it's not obvious to all why this is the best, so let's be explicit:

Dates in this format can be sorted lexicographically

It's also unambiguous. Nobody uses yyyy-dd-mm, whereas xx/xx/yy can be misinterpreted.

I distinctly remember SQL Server 2000 pulling that one on me. I had switched a DB app over to using ISO dates exclusively in its queries to avoid the month-day-ordering confusion and then the bloody thing earnestly started to parse yyyy-mm-dd dates as yyyy-dd-mm at every chance it got. So much for unambiguous date formats!

Apparently, Kazakhstan uses yyyy-dd-mm, but only in Kazakh (not in Russian.)

I guess if we are only talking about English speakers, that’s not an issue, since if Kazakhs don’t write dates that way in Russian, I presume they wouldn’t do it that way in English either

My (and every other) Swedish social security number uses this format plus 4 more digits. It ends up being the format I usually default to when writing a date. I feel like it is the least likely to be misconstrued, when I start with the full year. Would many people ever mistake it for yyyy-dd-mm?

As an Indian who thinks of date as (in order) day → month → year for me dd-MM-yyyy is the standard.

But given a choice I'd prefer something like dd-MON-yyyy because there is such an incongruous mixture of dd-MM and MM-dd across Indian services that often you are not sure unless one of the numbers crosses 12.

A nice thing about yyyy-mm-dd, in addition to being the standard, is that since no one uses yyyy-dd-mm it's unambiguous

As a canadian, i'm pretty sure i've never seen anyone use that date format.

If you do your taxes on paper, you'll have entered your date of birth in that way (upper right corner): https://www.canada.ca/content/dam/cra-arc/formspubs/pbg/5015...

Fair. Also i just realized that cheques also use that format.

Colloquially though i dont see that format very much.