February is the shortest month of the year, but February gets an extra day every four years. The reason this happens is because a year is the total amount of time it takes the Earth to make a full orbit around the sun. This is not the whole number of days like how the calendar shows a year is 365.2422 days long. This is the reason that February has an extra day every four years.
This would still put us off a little bit every year because our years would be 365.25 days long instead of 365.2422 days. That is a .007799-day difference in the time it takes to finish a year. This adds up over time so we have more rules for leap years that are lesser known. The way we get around this problem is by rounding to 365.2425 days which only gives us a difference of .00029 days which is a major time save. The way the calendar makes this happen is by making almost every one hundred years not a leap year. The reason why it is not every one hundred years is because if the year is divisible by four hundred, then it will still be a leap year. An example of this is that the year 2000 was a leap year because it is divisible by four hundred but the year 1900 was not a leap year. The math behind this checks out and is pretty simple. The equation is 365 plus 1/4 minus 1/100 plus 1/400 which would equal 365 and 97/400 which if you convert that into a decimal, it is 365.2425.
The most used calendar is called the Gregorian calendar but even back in ancient times, people had leap years. Julius Caesar made a calendar back in the year 45 BC called the Julian calendar. This calendar only had a leap year every four years which is less accurate and would lose about three days every four hundred years. This may not sound like a lot but if we still used this calendar today, we would be approximately 15 days off on our calendars.
The reason the extra day was added to February in particular is because February is the shortest month. It has been the shortest month since before the Julian calendar was alive because February was created for the Romans to honor the dead. The Romans used this month in particular is because they believed that even numbers would bring bad luck, and February was the only month in their calendar that had an even number of days. The most unlucky people in any society are the dead, so the Romans decided that February would be used as a month to honor their fallen people.
People born on February 29 are in a gray area of birthdays because they can either celebrate it on February 28 or they can celebrate it on March 1. Some countries put laws into place for people born on leap days like Taiwan which makes the birthdays February 28 and Hong Kong considers the birthday to be March 1. Both dates are acceptable solutions to the problem.
All in all, the leap year is a necessary addition to our modern calendars because without it we would lose our way to keep track of time.
