UTC

From Help With Kumu Wiki

Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time (GMT). For most common purposes, UTC is synonymous with GMT, but GMT is no longer precisely defined by the scientific community.

Time zones are usually defined to differ from UTC by an integer number of hours, although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. Several jurisdictions have established time zones that differ by an integer number of half-hours or quarter-hours from UT1 or UTC.

UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). For example, UTC is 5 hours ahead of (that is, later in the day than) local time in Ontario Canada during winter, but 4 hours ahead while daylight saving is observed there.

More information can be found in the Wikipedia article http://en.wikipedia.org/wiki/Coordinated_Universal_Time