Even though it happens every four years, many of us can still forget when we're in a leap year and that extra day can cause all manner of confusion.
The extra day in February which extends the year to 366 days - and is traditionally said to be a day for women to propose - is needed to keep the calendar year synchronised with the Earth's movements around the sun.
With 2020 being a Leap Year, that additional day - February 29 - is this Sunday and it can give us pause if, for instance, we're weekend workers wondering if it means we're due an extra day's pay - and you may have to check your contracts for the answer .
But another point which comes to mind is, what if you're born on February 29? With that elusive day coming around only every four years, when is your birthday in the meantime?
And, importantly, is there any legal answer to the question of which date to celebrate a February 29 birthday in a non-Leap Year?
It can make a difference - although rarely - in matters such as driving licence expiry dates and when it's legal to take that first alcoholic drink.
It turns out that in legal terms, a Leap Year birthday can fall on either February 28 or March 1 depending on the country of birth.
In England a Leap Year baby turns in age on March 1 during non-Leap Years. And as Hong Kong is a former British colony, the situation is the same there.
But both New Zealand and Taiwan make the non-Leap Year birthday February 28, as - it is believed - does the occasional US state.
However, the decision of when to celebrate is, of course, entirely up to those concerned.
In an interview some years ago with The Chronicle's sister paper The Journal, White Mischief actor Joss Ackland told how he had just celebrated his official 21st birthday - at the age of 84.
