Coordinated Universal Time (UTC)

Coordinated Universal Time (UTC) is a compromised time scale introduced in 1972.  To ensure that UTC is kept within 0.9 seconds of UT1, provision was made for the introduction of "leap second" in the UTC scale whenever necessary.   Thus, UTC differs from International Atomic Time (TAI) by an integral number of seconds.  The decision to introduce a leap second in UTC is the responsibility of the International Earth Rotation Service (IERS) in Paris.