Why Do We Have Leap Days? 

Usually, there are only four Mondays in February. But this year's February is weird*: It'll have five Mondays. Why? It's leap year! A lot of folks get confused on why exactly we even have leap years. The answer is simple. Wait! No it's not! It's actually a mess. But together with the good folks at Slate I have tried to simplify it for you in video form: See? Now, in that video I skipped a few things, and rounded the numbers a lot to make it easier to grasp. If you want the details -- and it's m...