For three years it was possible to do without it. But now it's become necessary again. This coming New Year's Eve, the radio controlled clocks will, after 0:59:59, instead of jumping to 1 o'clock at the next tick of the second, pause shortly in order to insert a small portion of extra time: a leap second.
The International Earth Rotation Service (IERS) in Paris has prescribed this addition to coordinated universal time (UTC …