As the end of February approaches, many are wondering when the next leap year is and how often they occur.
Leap years tend to take place every four years, leading many to search for answers to a host of questions about them, and their origins.
This year - 2021 - is not a leap year, meaning there are 365 days in the annual calendar this time around, but the next one isn't far off.
When was the last one, when is the next one, and why do we have them at all? Read on to discover all there is to know about leap years.
What is a leap year?
A leap year is a year in which an extra day - 29 February - is added to our annual calendars.
The 29 February is known as Leap Day and anyone born on this day is generally referred to as a Leapling.
Leap years occur every four years.
Why do we have a leap year?
Broadly speaking, leap years happen every four years to keep our calendars in sync with the seasons.
There are 365 days in the Gregorian calendar - used in most parts of the world, including the UK - but it takes the Earth a little longer to complete a full orbit of the Sun.
A full orbit of the Sun takes 365.25 days so an extra day is added to the calendar every four years to correctly align the solar year with the astronomical seasons.
If the day was not added then the calendar would be out of sync by five hours, 48 minutes and 45 seconds each year, which could have a big impact over time.
It could see a big shift in the seasons as we know them, as they move a day every four years, which could lead to winters in June and July and summers in November and December months.
How many days are in a leap year?
There are 366 days in a leap year - one more than the usual 365 days.
When was the last leap year?
The last leap year was in 2020. On 29 February 2020, South Korea reported 3,150 confirmed cases of coronavirus, as the outbreak began its grip across the world.
When is the next leap year?
The next leap year will take place in 2024. The next Leap Day will be Thursday 29 February 2024.
After that, leap years will take place in 2028, 2032, 2036, and 2040.
Leap year folklore
People born on the 29 February believe it to be a sign of good luck - though can only celebrate their official birthdays every four years - which might not be as much fun as being born on either the 28 February or 1 March.
Leap Day was also known to be a time when women were able to propose to men, rather than the other way round, though this tradition has fizzled out in more recent years.
It is considered bad luck to get married during a leap year in Greece. Superstition says that couples that tie the knot in a leap year are more likely to get divorced.
In Scotland, leap years are regarded as bad years for livestock after an old saying "leap year was ne'er a good sheep year". Though its origins are not clear, Scottish farmers tend to take extra care on 29 February.