Universal Time Coordinated (abbreviated to UTC) is the primary time standard by which the world regulates clocks and time.
It is within about 1 second of mean solar time at 0° longitude, and is not adjusted for daylight saving time. In some countries where English is spoken, the term Greenwich Mean Time (GMT) is often used as a synonym for UTC. Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM). It is also known as "Z time" or "Zulu Time".