The yyyy-mm-dd format (ISO 8601) is the only one that is unambiguous, because no one so far in history has ever used the yyyy-dd-mm format (at least until some xkcd-reading jokester probably will start using it just out of spite). I use ISO 8601 everywhere. It has the additional benefit that filenames get sorted correctly in lexographical order.
Date formats. Can never tell if dd/mm/yyyy, mm/dd/yyyy, yyyy-mm-dd…
The yyyy-mm-dd format (ISO 8601) is the only one that is unambiguous, because no one so far in history has ever used the yyyy-dd-mm format (at least until some xkcd-reading jokester probably will start using it just out of spite). I use ISO 8601 everywhere. It has the additional benefit that filenames get sorted correctly in lexographical order.