International Date Format Campaign
The Internet is a truly International method of communicating – there are no political or cultural boundaries drawn on the www page you call up – the page could have been stored in the Smithsonian Institute or on a small server in a basement in Ulan Bator, Mongolia. Often, you have no way of telling. So, if anyone in the world can read your page, why not ensure that any date references on that page can be read correctly and unambiguously by that person, by using the ISO 8601:1988 International Date Format.
So what is this date format?

CCYY-MM-DD

where CC is the century (representing the digits used in the thousands and hundreds components, as opposed to the actual century), YY is the year, MM is the month of the year between 01 (January) and 12 (December), and DD is the day of the month between 01 and 28 or 29 or 30 or 31, depending on length of month and whether it is a leap year. These dates are using the Gregorian calendar.

For example : 2001-01-15 is the fifteenth of January in the year two thousand and one A.D. – completely unambiguous

Agreed!!