A couple of months ago, around the time that incredible second trailer for Star Wars: The Force Awakens came out, I happened to be visiting my father, a Star Wars fan since ‘77 who introduced me to the films when I was three or so. He hadn’t seen the trailer yet, so I showed him. He was suitably impressed by what he saw, but since he’s someone who doesn’t spend his days on the internet like I do, he had some questions, including one that I would imagine more than a few Star Wars-friendly Dads have asked in recent months: “Is this based on any of the books?”

So, I had to explain something to my Dad, and from what I gather it’s something a lot of nerds have had to explain to a lot of their less nerdy friends over the last year or so. Thanks to Disney’s involvement, Star Wars continuity is changing, sometimes in very big ways, and if you’ve had a little trouble figuring out exactly what’s up (or you just didn’t bother to find out until now), I’m here to help. Here’s the deal:

(Some spoilers for things like Star Wars comics to follow…)

The books my father was referring to are a big chunk of the massive, murky, decades-long venture known as the “Star Wars Expanded Universe.” The EU (as the cool kids say) technically started in 1978 with the first comics and novels spinning out of George Lucas’ original 1977 film, and though it continued through the '80s, it really took off in the early '90s with The Thrawn Trilogy, a series of really fun novels by Timothy Zahn billed as the official sequels to Return of the Jedi. The books sold millions of copies, re-energized Star Wars fandom, and helped drive a wave of new material in the EU that included comics, many novels from throughout the universe’s timeline, video games, and more.

My Dad asked about “the books” because for many years they were the official story, and after reading them I’d explained to him in detail what happened to his favorite characters after Jedi. Han and Leia got married and started a family, Leia was the Head of State of the New Galactic Republic, Luke continued to rebuild the Jedi Order, and they all worked together to battle remnants of the Empire and clean up the galaxy. Only, that’s not the official story anymore, and if you aren’t following Star Wars that closely and were already a little confused by the relationship between the books and the new films, you might’ve been even more confused when you saw this little nugget floating around the internet this week:

That’s a page from Star Wars #6, released by Marvel Comics this week. Yes, it’s real, and yes, it counts. Before The Empire Strikes Back, Han Solo was married. We don’t know for how long, and we don’t know if it’ll stick, but he was married. It’s a big development, big enough to send Star Wars fans who’ve basically only followed the films into a minor panic if they happened to see this news floating around on the web. Han Solo is a character people have been writing “official” stories about for nearly 40 years, including stories set during the original trilogy, and never once was a wife mentioned, so why is this coming up now?

Because, quite simply, all those stories aren’t official anymore.

Pretty much everyone knows that Disney bought Lucasfilm, and by extension Star Wars, in 2012, with the intention of making new Star Wars movies. What fewer people know, because they’re not hunched over a laptop scouring the nerd internet all day like I am, is that in April 2014, Disney erased pretty much the entire Star Wars Expanded Universe from official continuity. Those Thrawn books I was talking about earlier? They don’t count anymore. Neither do all the comics published by Marvel in the '70s and '80s and Dark Horse in the '90s and '00s, or the Shadows of the Empire video game everyone with a Nintendo 64 had, or any of the other novels, comics, and games generated in the decades since Star Wars debuted. You can still go buy those books under the “Star Wars Legends” banner, but they’re not the official story anymore. They’re an alternate history, what Marvel would call a “What If?”

Disney did this because they wanted to make their own big-budget, big-screen sequel to Return of the Jedi, and they didn’t want to have to contend with years of official Han/Luke/Leia canon to do it. So, rather than navigating years of complicated, sometimes even contradictory Star Wars continuity, they simply erased it and started over. Now Disney gets to not only weave its own post-Jedi tale, but seize the big pile of gold that comes with creating its own Expanded Universe. New books, new comics (from Disney-owned Marvel, naturally), new video games, and new TV shows are all either already here or on the way, and they’re the future of the hyper-detailed Star Wars canon nerds like me will obsess over in decades to come.

Now, I said “pretty much” the whole Expanded Universe earlier, and that’s because not all of it went away. One thing got to stay, and that’s Star Wars: The Clone Wars, the acclaimed animated series set between the second and third prequel films (available on Netflix if you are so inclined). The series began pre-Disney, but it ended post-Disney, so it stays to add a nice layer of stories that are frankly more enjoyable than big chunks of the prequels anyway. Beyond that, there’s the original six films (of course) and anything that says “Star Wars” released by Disney and its affiliates after April 2014. So, the new animated series Rebels, the new Marvel Comics, the new novels, and anything else Disney decides to launch all count. Disney’s got big plans for Star Wars, and it’s all being carefully managed by a “Lucasfilm Story Group” so that it all (hopefully) makes sense going forward.

There, now you have a firm grasp of how Star Wars continuity has changed over the last couple of years. Go forth and tell your friends, you big nerds.