Happee birthdae Harry, indeed. This weekend is not only Harry Potter's 36th birthday but also the release of the eighth story in the magical series. Are you ready?

"It was always difficult being Harry Potter and it isn’t much easier now that he is an overworked employee of the Ministry of Magic, a husband and father of three school-age children," reads the Pottermore summary of "Harry Potter and the Cursed Child," a script-book to be published Sunday. "While Harry grapples with a past that refuses to stay where it belongs, his youngest son Albus must struggle with the weight of a family legacy he never wanted. As past and present fuse ominously, both father and son learn the uncomfortable truth: sometimes, darkness comes from unexpected places."

If you're headed to a midnight release party for the new book, you should be prepared for trivia contests. Here are 17 Harry Potter facts you didn't know, mostly collected from TIME, Mental Floss and BuzzFeed:

The franchise is worth something like $15 billion.

Daniel Radcliffe, the actor who played Harry in the movies, wore about 160 pairs of glasses during filming.

Tom Felton, who played Draco Malfoy, initially auditioned to be Ron Weasley or Harry.

Watching all the movies would take you almost 20 hours.

The final book, "Harry Potter and the Deathly Hallows," could have been titled "Harry Potter and the Elder Wand."

At one point, the actors who played the trio had to write essays about their characters. Rupert Grint — Ron — didn't do it.

J.K. Rowling said she always envisioned Albus Dumbledore as a gay character.

Before settling on "Granger," Rowling considered making Hermione's last name "Puckle."

There are four Wizarding Worlds of Harry Potter, which are themed parks based on the series. Two are in Florida, one is in California and one is in Japan.

There were two Dumbledores in the films: Richard Harris, who died in 2002, and Michael Gambon, who was cast in his place.

The first book was released in 1997.

The final movie came out in 2011.

There's an actual Platform 9 3/4 sign at King's Cross train station in London. Tourists can take photos underneath it.

Rowling has the same birthday as Harry. This year, she'll be 51.

Radcliffe's eyes aren't green in the movies because he was allergic to the contacts that would have changed his eye color.

There are more than 573,000 Potter fan fiction stories listed on fanfiction.net. 

The books have been published in more than 70 languages.