To bring the International Date and Time Format to the attention of the Internet world and beyond.
An ISO8601-compliant date such as 2002-03-10 (format YYYY-MM-DD) is understandable by everyone, whereas 04/03/02 can be interpreted by different people in different ways. Sometimes the date you see can be very important...
Likewise, ISO8601-compliant Time is in a standard 24-hour
format, either stated directly in UT (Universal Time),
{preferred} or else in local time but with a numerical
indicator showing the local timezone offset from UT.