Despite popular belief, leap day is not the gregorian calendar inter-calculation. In fact, leap day is the day on which Irish women are called to jump as far as they can in hopes of making it to the next month.
In all seriousness, that isn't very true...at all...in any shape, form, or alternate state.
Leap day, in reality, is the summation of four "1/4days" put together to create a full day. In our calendar, which is gregorian (the western calendar accepted ever since Pope Gregory XIII), a year is 365.25 days long. Despite the 1/4 at the end of it, we consider a year to be only 365 days long. So what do we do with the extra 1/4 you ask? We make up for this discrepancy every 4 years by adding an extra day in February: the 29th! We call this process inter-calculation (inter-calculation is just a big word for the insertion of an additional day to keep our calendar in line with the solar cycle). So every fourth year, we have 366 days! How awesome is that!?
This is necessary so that 400 years or so from now, our sun would not be completely out of whack with our own calendars due to the offset...the moon would be in the wrong place with the sun and the earth would turn on axis, spinning closer to its eventual doom within the sun. All of that would result in endless explosions, earthquakes, tsunamis, and countless disasters of all kinds, which would gradually get worse and ravage the world till civilization teetered on the precipice of extinction.
Because our calendars would be off.
As you may have noticed by now, I'm practicing my sarcasm. None of this would happen. Really guys...don't believe it. Put away your backpacks and baseball bats, an apocalypse is not going to occur. The only problem would be that our days wouldn't exactly line up with the sun; this problem would get worse as time progressed. The interesting truth about leap day is that many people consider it to be a holiday. To others, it carries a quality of mystical European romance. Many folk traditions are observed on this day, including an Irish day of female proposals (popularized by the movie, "Leap Year"), a Scottish day of compensation for female proposal denials, as well as other strange traditions. One thing surrounds these traditions, the reversal of male and female roles. One could wonder why the traditions concern women, but the truth behind it is that leap day is a fascinating day for all. Whether you are going to propose to your boyfriend or go prepare for an apocalypse, make the best out each day of the this year, you only have 366!
And remember, this year is longer than the last, make sure you make that extra time count!