Greenwich Mean Time (GMT) (GMT)

Mean solar time at the Greenwich meridian, now commonly used as the name of the UTC+0 civil time zone in the United Kingdom.

Historically, GMT was an astronomical time standard derived from Earth’s rotation. Modern navigation and technical communications normally use Coordinated Universal Time, an atomic time scale maintained close to UT1.

In everyday UK usage, GMT denotes winter civil time and is one hour behind British Summer Time. GMT and UTC often show the same clock reading, but they are not identical technical definitions.