Coordinated Universal Time

Coordinated Universal Time (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 and is not adjusted for daylight saving time. UTC was established in 1960 by the International Telecommunication Union and is maintained by the Bureau International des Poids et Mesures (BIPM) in Paris using a weighted average of over 400 atomic clocks worldwide. The name 'UTC' is a compromise between the English 'Coordinated Universal Time' and French 'Temps Universel Coordonné' — neither abbreviation matches, so the neutral 'UTC' was chosen. UTC replaced Greenwich Mean Time (GMT) as the international standard in 1972. Leap seconds are occasionally added to UTC to keep it within 0.9 seconds of UT1 (astronomical time), though there have been proposals to abolish leap seconds. UTC is used in aviation (pilots use 'Zulu time,' where Z = UTC), military operations, space missions, internet protocols (NTP), programming (Unix timestamps count seconds since 1970-01-01T00:00:00Z), and international law. Most programming languages default to UTC for date/time operations, and databases typically store timestamps in UTC to avoid timezone ambiguity.