Do you know? What is Leap second

Leap second is a one second adjustment applied to the UTC (Coordinated Universal Time) to manage the time difference generated by irregularities in the earth's rate of rotation.

The first correction was made on 1972 and a total of 26 such corrections are made. The next leap second revision will be on the end of June 30, 2015 at 23:59:60 UTC.

International Earth Rotation and Reference Systems Service (IERS) decides and approves this changes.