Happy birthday to all those technically turning six today.
Age can be a touchy subject for some, but those born on February 29 will be eternally young and - in terms of celebrating the actual day they were born - only get older every four years.
People born on February 29 will usually opt to celebrate their birthdays on February 28 or March 1 when it's not a leap year, because no one wants to miss out on presents, do they?
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The chances of being born on February 29 are actually very slim, with there being about a one in 1,461 chance of being born on the date.
There are some famous faces who were born on February 29 - Ja Rule included.
The rapper was born on February 29, 1976.
Indiana Pacers star Tyrese Haliburton is also a leap year baby, as well as Los Angeles Chargers' Eric Kendricks.
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Law & Order actor Peter Scanavino marks his birthday today too.
Meanwhile, triplets Savannah, India and Alicia Phillips, from Wolverhampton, UK, are an example of those celebrating their 'sixth' birthday today.
The three young women were born in 2000.
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In light of them being born on February 29, on years that aren't a leap year, the trio mark their birthdays on varying dates.
"I always want my birthday a day earlier," India told BBC Radio WM. "Any excuse."
But Savannah argued: "As you get older you'd rather delay your birthday by a day, right?"
As to why we have leap years, it's a little bit more complicated than you'd think.
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It's because each year isn't technically 365 days long.
It actually takes Earth 365.242190 days to orbit the Sun - and the .242190 is the entire reason we have an extra day (almost) every four years.
The Julian calendar is first thought to have introduced the leap year so that the tropical calendar coincided with the solar calendar, but this worked under the assumption that it took the Earth 365.25 days to orbit the Sun.
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This was actually 0.0078 days longer than the tropical year, so Pope Gregory XIII introduced some amendments to Julius Caesar's calendar in the 16th century so that leap years weren't quite every four years.
There won't be a February 29 in 2100, 2200, 2300, for example.
Whatever age you might be turning today, happy birthday and make sure to make the most of it - especially if you only celebrate every leap year!
Niamh Shackleton