Why do we even have leap year? Well as it turns out, it does not take the earth 365 days (1 year) to orbit the sun. It actually takes it aroudn 365.25 days to orbit the sun. This accounts for an extra 6 hours that is missd every year. The solution? An extra day every 4 years.
6 hours multiplied by 4 is 24 hours (a day), so the leap year only comes once every for years.
Enjoy the extra day!