Did you know that today, the daily hours will gain an additional second worldwide, following a rare phenomenon called ‘leap second’. So today, every of you will get your extra one second for free.
A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earth's rotation drifts away from atomic time because of irregularities in the Earth's rate of rotation.
Since it firs implementation in 1972, 25 such leap seconds have been inserted. The most recent one(the 25th) happened on June 30, 2012 at 23:59:60 UTC. A leap second, the 26th, will again be inserted at the end of today; June 30, 2015 at 23:59:60 UTC.