February 29th comes up on the calendar only every four years. A year with a February 29th might be good news if you are paid by the day or the week. But it might be bad news if you were born on a February 29th. You have to wait three years in between birthdays!
American English has an expression for the unusual situation. February 29th is called a leap day. And the year with a February 29th in it is called a leap year. This year, 2020, is such a year.
As a verb, the word "leap" means to jump, or to move quickly. "Leap" can also be a noun, meaning a jump, or a sudden move.
In a leap year, the dates jump over one day of the week. Let me explain. In 2017, the last day of the year, December 31th, fell on a Sunday. In 2018, it fell on a Monday. In 2019, it fell on a Tuesday. But in 2020, December 31th will fall on a Thursday. It jumps right over Wednesday.
The reason for a leap day or a leap year is because our calendar does not follow the Earth's orbit(轨道) around the sun exactly. Each year, we have a little time left over. So every four years, we put all that time together into an extra(额外的)day.
Some people choose to marry on February 29th because it is an unusual date. But some ancient peoples would likely tell couples not to do it. Leap years were believed to be difficult, and leap days were unlucky. To be honest, these have no scientific basis(依据).
