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.
Interesting. So over the course of existence, we add a random second to time to compensate for the rotation of the earth.
Because the Earth's rotation speed varies in response to climatic and geological events, UTC leap seconds are irregularly spaced and unpredictable. Insertion of each UTC leap second is usually decided about six months in advance by theInternational Earth Rotation and Reference Systems Service (IERS), when needed to ensure that the difference between the UTC and UT1 readings will never exceed 0.9 second. Between their adoption in 1972 and June 2012, 25 leap seconds have been scheduled, all positive.
I thought this was pretty cool haha. So either our clocks would have to add one second randomly to time when this leap second comes into play, or we slowly add milliseconds to time itself to eventually compensate for this added second.
You learn something everyday. =)