Definition and Relationship To Other Standards
The current version of UTC is defined by International Telecommunications Union Recommendation (ITU-R TF.460-6), Standard-frequency and time-signal emissions. UTC is based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the Earth's slowing rotation. Leap seconds are used to allow UTC to closely track Universal Time (UT1), as explained later in this article.
The difference between UTC and UT1 is not allowed to exceed 0.9 seconds, so if high precision is not required, the general term Universal Time (UT) may be used. The term Greenwich Mean Time (GMT) does not have a precise definition at the sub-second level, but it is often considered equivalent to UTC or UT1. Saying "GMT" often implies either UTC or UT1 when used within informal or casual contexts. In technical contexts, usage of "GMT" is avoided; the unambiguous terminology "UTC" or "UT1" is preferred.
Read more about this topic: Coordinated Universal Time
Famous quotes containing the words definition, relationship and/or standards:
“Mothers often are too easily intimidated by their children’s negative reactions...When the child cries or is unhappy, the mother reads this as meaning that she is a failure. This is why it is so important for a mother to know...that the process of growing up involves by definition things that her child is not going to like. Her job is not to create a bed of roses, but to help him learn how to pick his way through the thorns.”
—Elaine Heffner (20th century)
“From infancy, a growing girl creates a tapestry of ever-deepening and ever- enlarging relationships, with her self at the center. . . . The feminine personality comes to define itself within relationship and connection, where growth includes greater and greater complexities of interaction.”
—Jeanne Elium (20th century)
“It gives me the greatest pleasure to say, as I do from the bottom of my heart, that never in the history of the country, in any crisis and under any conditions, have our Jewish fellow citizens failed to live up to the highest standards of citizenship and patriotism.”
—William Howard Taft (1857–1930)