Coordinated Universal Time or UTC is now the world’s time standard it took over from the old Greenwich Meantime (GMT) after the development of atomic clocks. UTC is based on GMT but accounts for the random variations of the Earth’s rotation by having leap seconds added once or twice a year.
By accounting for the Earth’s rotation, UTC can keep noon above the meridian line (as GMT) but can also be recorded by the highly accurate atomic clocks.
UTC is ‘Universal’ in that it allows the entire world to communicate with the same timescale. For us humans UTC accounts for the time-zones by having a positive or negative integer after the time. Here is the UTC time zones:

Fortunately computers aren’t bothered about timezones and when communicating together across global networks via a time server UTC is the same no matter where they are on in the world.
Computer time servers usually receive their UTC time from a source external to the internet such as the GPS signal which are directly broadcast via atomic clocks in doing so a time server can keep a computer network to within a few milliseconds of UTC.