Harry Potter fans were up early on Saturday getting stuck into the sixth book which has finally hit the shops.
Many shops opened at midnight to sell The Half-Blood Prince to readers who were desperate to get their hands on the latest wizarding adventure.
Shopkeepers are expecting more than 10m copies to fly off the shelves on Saturday too, make it the fastest-selling book ever.
One book chain said copies were being sold at the rate of 13 per second.
It's thought up to 300,000 UK fans queued to get the book at midnight.
And you are already well into the book. You've been e-mailing and texting us all day telling us your first thoughts.
Some of you have already been in tears, and one reader told us his parents had to take the book away from him as he was reading it in the middle of the night and was too tired!
Newsround Online joined kids as they queued for hours in London and Edinburgh and loads of fans sent texts to us in the countdown.
Many book stores put on readings, parties and performances to keep them happy.
Olivia, from London, and Jamie, from Canterbury, kept busy by writing blogs for the Newsround website.
In Edinburgh, JK Rowling enthralled 70 lucky young fans with a midnight reading inside the city's castle.
The building was dramatically illuminated with a Harry Potter image.
Fire-eaters, torch-throwers and jugglers kept the crowd entertained.
The castle's entrance, filled with pretend smoke, was decorated to resemble the Hogwarts' entrance hall.
At a minute past midnight, JK emerged from behind a secret panel to read the sixth chapter of the new book
She introduced Harry to the world in 1997 and since then the books have sold 270 million copies in 62 languages.