If you’re anything like me, you’re not particularly schooled on the nitty gritty details of why we have leap years. I know it occurs once every four years when we add a February 29th to our calendars, and I know we do it to keep our calendars in sync with the earth’s rotation, but other than that, I’ve always just associated leap year with a kid I grew up with who only had one real birthday every four years.

He would celebrate every February 28, but I always imagined it wasn’t the same. Also, I read recently that children born on February 29 used to be called “leapers” or “leapings” and that superstitious parents didn’t want a February 29 due date because they thought a “leaper” would “inevitably prove sickly and ‘hard to raise.’” So I felt bad for that kid, but that’s about it.

Obviously, there’s a lot more to it and it’s all pretty interesting. This video going around the Internet this morning does a pretty swell job at summing up why we have leap years and how they work. It’s worth four minutes if you got them.