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.