September 1st 2017 marks the day Harry Potter put his son Albus on the Hogwarts Express

It's a special day

JK Rowling / Harry Potter book / Young actors

The 1st of September 2017 is the date the famous wizard sends his son Albus Severus Potter to Hogwarts for the first time. To celebrate this special date JK Rowling tweeted earlier, 'Albus Severus Potter boards the Hogwarts Express at King's Cross for the first time #19yearslater'.

Here are 19 things we've learnt from Harry Potter:

1) Despite her pen name JK Rowling, the author doesn't have a middle name. For the release of her first book her publisher, Bloomsbury, asked that she used two initials, rather than her full name Joanne Rowling, as they thought boys might not want to read a book written by a woman. She chose K for Kathleen which is her paternal grandmother's name.

2) JK Rowling wrote her books so the characters would grow up with the children who were reading them. Each book took place over a school year and as the characters grew up the books became longer and darker.

JK Rowling

JK Rowling © PA Images

3) Harry Potter isn't without its mistakes, there are a number of errors in the books, some to do with the order things happen or the floors on which classrooms are. JK Rowling reportedly said, "Several classrooms move floors mysteriously between books and these are the least serious continuity errors! Most of the fansites will point you in the direction of my mistakes. But the essentials remain consistent from book to book because the story has been plotted for a long time and it is clear in my mind."

4) If you've got one of the first editions of the book it could be worth a lot! JK Rowling initially struggled to get her book published and was turned down by 12 publishing houses before Bloomsbury took it on. Not confident that it would be popular they only printed 500 hardback copies of the book and 5,150 paperbacks.

According to Peter Harrington, the UK’s largest rare bookseller, around 300 of the original 500 hardbacks were sent to schools and are no longer in good condition, meaning the remaining 200 have become very valuable, potentially being worth around £50,000.

Harry Potter and the Philosopher's Stone (book)

Harry Potter and the Philosopher's Stone © PA Images

5) As the books progressed more and more characters died. According to the main Potter fandom wiki, 158 known individuals have died, including some pretty major characters - don't worry, no spoilers here.

6) In the late 90s the Harry Potter Effect saw interest in boarding schools increase with some schools even building extra dorms!

7) As a single mum on benefits JK Rowling famously wrote her first book in Nicholson’s cafe and the back room of the Elephant House in Edinburgh.

8) In some places in the US copies of the books were burnt as people believed they were encouraging kids to take up witchcraft!

9) In 2010 a module called Harry Potter and the Age of Illusion was created at Durham University as part of a BA in Education Studies.

10) At the time the first book was published it wasn't particularly big news with the media concentrating on the new Prime Minister (Tony Blair) and the Spice Girls! This is in contrast to the release of the last Harry Potter book in 2007 when Asda and Bloomsbury had a bit of a falling out (see number 12)

Spice Girls / Tony and Cherie Blair outside Number 10 Downing Street

Spice Girls / Tony and Cherie Blair © PA Images

11) Supermarkets barely made any money from the sales of the best-selling books, dropping their prices to be competitive. Many independent bookshops reportedly bought their stock from Tesco as it was cheaper than directly from the publisher!

12) Ten years ago Asda was forced to apologise to Bloomsbury after they said the publisher was profiteering from the release of the last book Harry Potter and the Deathly Hallows. In response to this accusation Bloomsbury cancelled the supermarket's order for 500,000 copies, less than a day later Asda apologised.

13) Following the success of Harry Potter, particularly with adults, the publisher decided to release an adult version of the book, the difference, a more 'sombre' cover!

Harry Potter covers (children's and adults')

Harry Potter covers (children's and adults') © Amazon.co.uk

14) Despite JK Rowling's phenomenal success not everyone is a fan. In 2003 AS Byatt wrote for the New York Times, "Ms Rowling’s world is a secondary secondary world, made up of intelligently patchworked derivative motifs from all sorts of children’s literature."

15) JK Rowling and her publisher are pretty hot on copyright. If you publish a book set in Hogwarts you'll end up in court, however the author has given fans a way to come up with ideas online as long as they bear in mind two caveats. Don’t publish it commercially, and no adult themes!

16) Harry Potter merchandise comes in all shapes and sizes, some of it not exactly what JK Rowling would approve of. Everything from Harry Potter condoms to a vibrating broom have been made!

17) As Harry Potter fever swept the bookshops some of the releases were so secretive that translators would not be given the English version until the last minute. According to reports French translators would receive the English copy as it hit the shelves and would work in teams, non-stop to get the book translated!

Harry Potter in French

Harry Potter in French © PA Images

18) JK Rowling doesn't just write about Harry Potter, in 2012 she published her first book for adults, The Casual Vacancy. The Casual Vacancy was very different from her previous books covering class, politics and religion, as well as discussing drug abuse and rape.

19) In 2013 JK Rowling published a book called The Cuckoo's Calling under the pseudonym Robert Galbraith. It took just three months for the Sunday Times to reveal who 'he' really was.