Today we are talking about the somewhat unusual day of February 29 . It comes up on the calendar only every four years . A year with a February 29 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 29 . You have to wait three years in between birthdays ! In any case , American English has a term for the unusual situation . February 29 is called a leap day . And the entire 12 month period with a February 29 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 31 , fell on a Sunday . In 2018 , it fell on a Monday . In 2019 , it fell on a Tuesday . But in 2020 , December 31 will fall on a Thursday . It just leaped right over Wednesday . The reason for a leap day or a leap year is because our calendar does not follow the Earth's orbit 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 day – or , what is officially called an intercalary day . But I have never , ever heard an English speaker use that term . “Leap day ” is fine . “Leap ” is also an important word for two other common – but opposing – American expressions . One is a kind of warning . If you want someone to investigate a situation completely before taking action , you might say , “Look before you leap .” The other expression is a phrase of hope . Urging someone to “take a leap of faith ” invites the person to take action , even if not everything about a situation is known . Interestingly , both phrases are completely reasonable to say to someone who is about to get married . On that note , some people choose to marry on February 29 because it is an unusual date . The ceremony is followed by a chance to skydive together – that is , jump out of an airplane with a parachute . But some ancient peoples would likely tell couples not to do it . Leap years were believed to be difficult , and leap days unlucky and a bad time to begin anything new . Whatever you think about them , the change in the calendar will be gone soon enough . Then we can return to normal , and leap over February 29 as usual .