It's leap day, a once-every-four-years bonus you can thank Julius Caesar and Pope Gregory XIII for.
We add a day at the end of February every four years because it takes the Earth about 365.242 days to make a full orbit around the sun. So we take those .242 days, round 'em up slightly and present the world with February 29, an extra day of, well, work for me, campaigning for the GOP presidential hopefuls or, if you fancy yourself a CNN iReporter, leaping!
We thank the Roman emperor Caesar and the 16th century pontiff for putting the day into place.
In 46 B.C., Caesar decreed that under the Julian calendar, a day would be added in any year evenly divisible by four. However, accounting for the rounding up, that got the Romans a little ahead of themselves as far as time goes, according to no less of an authority on things involving watches and calendars than timeanddate.com.
That little discrepancy, which amounted to 11 minutes every year, had added up to 10 whole days by 1582, when Pope Gregory said he had no time for inaccuracies and created the Gregorian calendar, under which we mark our days to this day. Gregory also designated February 29 as the official leap day and set up some rules so that we'd never end up 10 days ahead of ourselves again.
Here's how that works: Leap year occurs in every year that is evenly divisible by four and every century year that is divisible by 400. Hence, while 1200 and 2000 were leap years, 1700 and 1900 were not.
This also means that in the United States, leap years are presidential election years, which means we can always look forward to that extra day of campaigning.