Manual:Timestamp

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  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. Never use wfTimestamp when inserting a timestamp into the database; this will break in Postgres and possibly other non-MySQL databases. Instead use DatabaseBase::timestamp, aka $dbw->timestamp, which converts a timestamp in one of the formats accepted by wfTimestamp to the format used for inserting into timestamp fields in this DBMS.

is a convenience function that returns a MediaWiki timestamp for the present time.

Datatypes
Here are the various timestamp datatypes used in the MediaWiki core: