Why do we have a leap year?

It takes the Earth slightly more than 365 days to revolve around the Sun. So we add another day to our year every fourth year, to keep the seasons more closely aligned with the calendar.

It takes the Earth about 365 1/4 days to orbit the Sun. It is not possible to include this as a fractional day each year, so every 4 years an extra day is added at the end of February which is called a leap day, February 29th.

Even so, there is not quite 1/4 extra day, so in years ending in 00 that are not divisible by 400, the leap day is omitted. 1900 was not a leap year, and 2100 will not be one.

Because in really takes 365 Days and 6 hours for the Earth to revolve around the Sun... so they add the extra 6 hours and after 4 years it adds up to 24 hours...thus making February 29th possibleBecause the earth takes 365 and 1/4 days to revolve once around the sun,

and it's much cleaner and makes a lot more sense to make the calendar

1 day longer every 4 years than to try to make it 1/4 day longer every year.