The Universal Time Coordinated (UTC) is the coordinated world time. It forms the international basis for determining the time in daily life. This time used all over the world is the reference time for all time zones and thus replaces Greenwich Mean Time(GMT). UTC time is a reference time used as a global standard.
As reference time the coordinated world time uses the international atomic time( TAI). It is identical to this except for the leap seconds that may be inserted at the end of June and/or December. The reference point for the coordinated universal time (UTC) is the longitude of 0 degrees. The GPS system time reference is directly coupled to UTC time, but it differs in that UTC time is periodically adjusted to the Earth's rotation by adding leap seconds. In 1988, the time difference between the two times was five seconds.
Coordinated Universal Time (UTC) is kept within one second of Universal Time(UT), which is the value for one leap second. UTC time is given in the form Hour, Day, Month, Year. The time indication then looks like this: 1412 UT, 12 May 2009.