Postboxes are hugely convenient tools for helping us get our letters and cards sent across the country without having to travel all the way to a proper post office.
But while millions of us make use of the Royal Mail's little red pillars every day, have you ever stopped to take a look at the markings on the front of the box?
Each postbox comes with a symbol printed underneath the letter slot, and while the origins of that symbol might seem obvious to some, others are only just realising what it means - and it has a rather interesting history.
It turns out the symbol - which contains letters such as 'GR' and 'ER' - can actually help date the postbox, as you can use the information to figure out the rough timeframe for when the box was made.
So what do the symbols mean?
Well, they're actually known as the Royal Cypher, and they're made up of the initials of whichever monarch was ruling the UK at the time that the postbox was put in place.
Most postboxes will have an 'ER' on the front to denote that they were made sometime during the reign of our previous monarch, Queen Elizabeth II, who was on the throne for 70 years until her passing in 2022.
But if your local postbox has a 'GR' on the front, then it's definitely more than 70 years old, as 'GR' boxes were put up during the reign of King George V, from 1910 to 1936, while 'GR VI' ones date back to the era of King George VI, from 1936 until 1952.
And now that King Charles III is our monarch, any new postboxes that may need to be made will use his Royal Cypher, which contains a 'CR' - with the first letter standing for the monarch's name and the 'R' meaning 'Rex', which is Latin for King or ruler.
Royal fans have been blown away by the news, with some vowing to take their children to try and find the oldest postboxes they can in their local area.
One person wrote on Facebook: "My youngest was absolutely fascinated by this and we've been out spotting them. We have a Victorian one that we are going to go visit."
While another added: "Really interesting - thank you! I think this has to be the best post I have ever seen on here!"
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