If you're a fan of J.K. Rowling's Harry Potter series (and let's be honest, who isn't?), then you might know why today's date is so special in the Potter universe.
You might recall, in the last chapter of Harry Potter and the Deathly Hallows, Harry takes his son, Albus Severus, to King's Cross Station in London to leave on the Hogwarts Express.
And because Rowling never leaves out a single, impeccable detail, she actually gave a specific date for those events: today, September 1st, 2017.
In case you don't remember the last chapter, "Nineteen Years Later"...
It’s basically the ultimate fan service chapter. Harry and his wife Ginny take their son to the Hogwarts express, Ron and Hermione take their son, and even Malfoy brings his son.
It gave fans a peek at what an older Harry, Ron and Hermione might look like.
As well as their adorable wizard offspring.
Since Rowling gave a specific date for the events, people were anxiously waiting for "nineteen years later."
Luckily Harry Potter fans only had to wait about ten actual years, since The Deathly Hallows was released in 2007.
And now that "Nineteen Years Later" is today, people have been celebrating en masse.
The cast of The Cursed Child play celebrated with an awesome Hogwarts Express shaped cake.
Harry Potter fans old and young alike have also taken to social media to celebrate #19YearsLater.
But the absolute best celebration was from an unlikely source.
You’ll definitely want to see what Rugby Station did to celebrate…