It's always intrigued me. Can an 80yr legitimately and legally say their are 20 ?
Leap years happen every fourth year, next one in 2020 and we gain a day in the Calendar on February 29th. So anyone born on that day, could or would only really celebrate a birthday every four years.
In reality some countries shift the legal status of the day to 28th Feb like New Zealand, but the trend is that your birthday would be legally recognised on the 1st March.
The thought of having your birthday shifted to satisfy a calendar change is an interesting one. There is now in fact a group of 29r's that refuse to accept this and want the advantage at least from a quirky point of view.
Anyway, I thought I would invade your brain today with questions about this. How prolific is this, do you have family or friends, work colleagues who are 29r's ?
Here's a good summary from Wikipedia -