Editing International Atomic Time (section)

== Relation to UTC ==
Contrary to TAI, UTC is a [[discontinuous]] time scale. It is occasionally adjusted by leap seconds. Between these adjustments, it is composed of segments that are mapped to atomic time by a constant offset. From its beginning in 1961 through December 1971, the adjustments were made regularly in fractional leap seconds so that UTC approximated [[UT2]].  Afterwards, these adjustments were made only in whole seconds to approximate [[UT1]]. This was a compromise arrangement in order to enable a publicly broadcast time scale. The less frequent whole-second adjustments meant that the time scale would be more stable and easier to synchronize internationally. The fact that it continues to approximate UT1 means that tasks such as [[navigation]] which require a source of Universal Time continue to be well served by the public broadcast of UTC.{{sfn|McCarthy|Seidelmann|2009|p=227&ndash;229}}