Wikipedia:Tip of the day/August 1, 2006
Customize appearance of dates
Under the "Date and time" tab in Special:Preferences, you may specify the format in which you view dates. This only works if the day-month and year are wikified so be sure to wikify complete dates when you see them. There is thus no need to change the markup language in the edit window to your preferred style. This customization has the salutary effect of keeping the American English and Commonwealth English Wikipedians from spending all their time revert warring over date syntax.
Read more:
Manual of Style (dates and numbers)