NEW YORK (PIX11) – In a few days, it will be Feb. 29 – also known as Leap Day.

But how does Leap Day actually work?

Leap years account for the Earth’s orbit, which is longer than 365 days by an additional six hours. Leap years keep the months of the year in sync.

Although many people believe leap years happen every four years, they do not. Usually, Leap Day is skipped once every 100 years. It happened in 2000, but will be skipped in the year 2100.

It can also be a pain for people with birthdays that fall on Feb. 29. Many government systems don’t include the date, so people have to use Feb. 28 or March 1.