Now, most people know that leap years (or leap days) exist, but most people don't know why, so I have decided to use this post (and this unique day) as inspiration.
Hopefully, you all know why a year has 365 days, but if you don't, it is because one year is calculated as the time it takes for the earth to do one full rotation around the sun (and, if you would like to know, a day is calculated by the amount of time it takes the earth to do one full rotation about it's axis). However, even though we typically say that it takes 365 days for the earth to rotate all the way around the sun, that is just an approximation. It actually takes 365.25636004 days for the earth to fully circle the sun. As you can see, (we are still rounding because it would be much more difficult using the full decimal) there is approximately an extra .25 of a day. This may seem like nothing, it is only about 1/4 of a day, or 6 hours, but if every year, the calender were off by 6 hours, after 100 years the calender will be off by 25 days, and after 500 years, the calender will be off by 125 days. This may seem irrelevant to daily life, but it would result in people trick-or-treating in the snow.
Hopefully this makes sense. After reading over it, it seems kind of confusing, so if you are confused, you can try this link I found that shows a guy who explains it a lot better than I do.
Anyways, I hope you all have a happy leap day because there won't be another one for four whole years! :)
Earth Rotating around the Sun (one year)
Earth Rotating about the Axis (one day)
HAPPY LEAP YEAR :)