Coordinated Universal Time, or UTC, is the primary time standard by which the world regulates clocks and time. It is within about one second of Mean Solar Time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used Prime Meridian) and is not adjusted for Daylight Saving Time. It is effectively a successor to Greenwich Mean Time (GMT).
The coordination of time and frequency transmissions around the world began on January 1, 1960. UTC was first officially adopted as CCIR Recommendation 374, Standard-Frequency and Time-Signal Emissions, in 1963, but the official abbreviation UTC and the official English name Coordinated Universal Time (along with the French equivalent) were not adopted until 1967.