[kbart]

I have never seen YYYY-DD-MM format, on the other hand, both DD/MM/YY and MM/DD/YY are equally common, that's why I always prefer YYYY-MM-DD format as it is the least ambiguous and most useful (sorting files etc., as other comments have mentioned). Feel free to prove me wrong though.

[oneeyedpigeon]

I work with non-techies. Most are totally unfamiliar with YYYY-MM-DD so weren't sure what a date that was ambiguous in that format was. I totally agree that usage of YYYY-DD-MM is rare (in my experience, anyway), but none of these formats fare particularly well when it comes to discoverability.

[robin_reala]

Have you ever been to any of Kazakhstan, Latvia, Nepal or Turkmenistan? https://en.wikipedia.org/wiki/Calendar_date#Gregorian.2C_yea...

[E-M]

I can assure you that Latvia does not use YYYY-DD-MM. Officially Latvia is using ISO 8601. https://en.wikipedia.org/wiki/ISO_8601#Usage

[robin_reala]

I’d update the Wikipedia article but don’t have time to go digging for official sources. Something you (or someone else with domain knowledge) could do?

[kbart]

I've been to Latvia many times in last few years, but haven't noticed YYYY-DD-MM format, maybe it's historical? It looks like DD.MM.YYYY was the most common format there (at least on posters).

[mixmastamyk]

Japan and Denmark use this format.