Remember the whole Y2K thing, where people freaked out that the Internet (which wasn't even all that great in 1999) was going to collapse and die when the clock struck midnight on January 1st 2000?
Well, there's a little of that hype in pockets of the Internet again this week, because on Tuesday an extra second will be added to clocks around the world.
A “leap second” has been added about every 18 months to make sure clocks are in sync with Earth, as it starts to rotate a tiny bit slower each year.
The last time it happened, a number of websites including LinkedIn, Reddit and Foursquare all crashed because their systems weren't ready for this extra second.
The second will be placed into network time services at the exact same moment worldwide, on June 30th at 23:59:60 UTC.
2011-12-31 23.59.60 <– leap second
Let's hope this time 'round, Facebook doesn't fall over...