Coordinated Universal Time , abbreviated as
UTC, is the primary
time standard by which the world regulates clocks and time. It is, within about 1 second,
mean solar time at 0° longitude; it does not observe
daylight saving time. It is one of several closely related successors to
Greenwich Mean Time (GMT). For most purposes, UTC is considered interchangeable with GMT, but GMT is no longer precisely defined by the scientific community.