Hey, hey! It's February 29th. Enjoy it; you won't see another one for 1,461 days. And be glad that it's not your birthday today, because you'd only get to celebrate your birthday on your birthday once every four years.
It's all about keeping the calendar working properly, of course. The Earth's year is 365.24 days long, and every fourth year, we have to add that extra day in February. Well, unless the year is divisibly by 100, in which case it's not a leap year, except when the year is divisible by 400, like 2000 was, which means that it is, indeed, once again a leap year.
Don't worry about that too much, since if you're old enough to read this, you're unlikely to still be around in 2100 when that becomes a problem again. If you are still around, you'll probably be too decrepit to care whether it's a leap year or not. I myself would be 139 years old in February 2100, which is currently long past my expiration date. It's possible that medical advances may make a 140-year lifespan attainable by the end of this century, but I'm not counting on it. I expect that the second number on the tombstone will start with a 20.
And on that cheerful note, get out there and enjoy your Leap Day!