Manual:Timestamp
From MediaWiki.org
The format of timestamps used in MediaWiki URLs and in some of the MediaWiki database fields is yyyymmddhhmmss. For example, the timestamp for August 9th, 2010 00:30:06 UTC is 20100809003006. The timezone for these timestamps is UTC.
MediaWiki's wfTimestamp() function provides a convenient way to convert from timestamps in common formats to the MediaWiki timestamp format and vice versa. Read Manual:wfTimestamp for more details.
