You've probably spent it reading this sentence - the "leap-second" added to the world's atomic clocks this morning.
The change at 09:59:59 (AEST) today adjusts for the inaccuracy of the world's clocks as the moon's gravity slows the Earth's rotation and knocks clocks out of alignment.
It's the 26th such adjustment since leap-seconds were introduced in 1972 after the invention of super-accurate atomic measurements.
The same principle governs leap-years, which keep calendars lined up with the Earth's orbit around the Sun.
Companies will be on alert, however, with previous leap-seconds having caused havoc with computer systems.
More than 400 Qantas flights were delayed after the most recent change in 2012 as computers crashed and staff switched to manual check-ins.
High-profile websites including Mozilla, Reddit, Gawker, LinkedIn, FourSquare and Yelp were also disrupted.
