UTC stands for Universal Coordinated Time. It is also termed GMT. GMT is Greenwich Mean Time. In 1884 in Washington, at an International Meridian Conference, this GMT time was declared a universal time standard. 24 time zone were created for all the countries and regions of the world.
Time of all the other regions of the world is coordinated with Greenwich Mean Time, hence it was named as Universal Coordinated Time (UTC). As all the time zones of the world coordinate with UTC, so the accuracy of its time is maintained with highly precise atomic clocks which ensures time accuracy of up to split seconds.
Here's a short description of UTC, its importance and the precise ticking clock of UTC time.
Coordinated Universal Time (UTC/GMT):
Incorporate the local offset in time to the UTC clock time. In this case, for example, if the local offset is -5:00 and you see the UTC times displayed as 11:00, you can add 5 to 11. The time setting that is adjusted to offset is 06:30 (6:00 A.M.). Note that the date is also in UTC format.