For the uninitiated, Dune can seem overwhelming. If you’ve actually read all the books, it can seem even worse!

Part of the brilliance of Frank Herbert’s Dune is the immensely layered, methodical world-building. This applies to the literal world of Dune itself, the planet Arrakis, as well as the history of the universe it occupies. Just when you think Herbert has used a shortcut to make his story seem more otherworldly, you’ll find he’s actually done his own homework about the world he actually built.

The proof of this is located right at the back of the first Dune book. In what I’ll broadly refer to as “the Glossary,” Herbert has included reference material to help guide you through the story. Guess what? You should read all that stuff first. If you don’t want to read Dune before that December 18 theatrical release, you should at the very least glance at the glossary. Here are six terms and ideas from the glossary and appendices of Dune that you should read first to maximize your enjoyment – and understanding – of this complex and awesome universe. Mild spoilers ahead.

6. Melange (spice)

If you don’t know what the spice is, you’re going to be in trouble. As the glossary describes, the Melange is “the spice of spices,” and it’s only found on Arrakis, the planet better known as Dune. This glossary entry also tells you that “Muad’Dib claimed the spice as the key to his prophetic powers,” and that “Guild navigators make similar claims.” The point is, you need the spice to see through space and time. Oh, and “Muad’Dib” is the name that Paul Atreides will eventually go by. Knowing this in advance is not a spoiler. On the very first page of Dune, the epigraph from Princess Irulan tells you that Paul and is the man who will become Muad’Dib.

OH. And never forget, prolonged exposure to the Spice makes people’s eyes turn blue-within-blue.

5. Mentat

Known as “human computers,” Mentat’s are not actually A.I. at all. (We’ll get to that in a second.) Instead, they are just highly-conditioned people who can think faster and smarter than most other people. This is important for many reasons, but from a plot point of view knowing what a Mentat is before you start reading Dune or watching Dune makes one specific revelation way more interesting.

4. “B.G” and “A.G.”

The dating system in Dune makes it a little difficult to pin down exactly when the events of the series take place relative to our own history. Roughly, the events of the first Dune novels occur 29,191 years in our future. We get this number by looking at events that happened “Before Guild” and “After Guild.” The Guild refers to the Spacing Guild which controls much of the commerce and, relies on the all-important substance of the Spice Melange. The terms “B.G.” and “A.G” when placed next to a year refer to “Before Guild” and “After Guild.” The B.G. years count down and the A.G years, naturally, count up. The role of Earth in the history of Dune is not entirely clear within the canon. The non-canon book The Dune Encyclopedia puts the earliest Terra (Earth) years at 19,000 B.G. Whereas the “expanded” prequels written by Herbert’s son, (like the book The Butlerian Jihad) are less specific on these dates. Either way, if somebody says “B.G.” or “A.G” in the new Dune that’s what those years mean. In all canons, Dune itself 100 percent happens in 10,191 A.G.

3. The Butlerian Jihad

Listed under “J” for “Jihad, Bulterian,” this term quickly explains why all the tech in the far future of Dune is so intentionally retrograde. Also known as “the Great Revolt,” this was a war against “computers, thinking machines, and conscious robots” from the years 201 B.G to 108 B.G. This conflict is not depicted in the Dune novels written by Frank Herbert at all. It is simply backstory and helps to explain why technology in the Dune universe is the way it is. One religious commandment from this era made it all the way into the “modern” era of the main story of Dune: “Thou shalt not make a machine in the likeness of a human mind.”

The Butlerian Jihad itself was depicted in the 2002 novel of the same name, written by Brian Herbert and Kevin J. Anderson. Not all Dune fans accept it as canon.

2. Bene Gesserit

You’re going to be hearing a lot about the Bene Gesserit once Dune actually comes out, so the glossary is pretty useful. In fact, on this subject, it’s useful twice. In the regular “Terminology of the Imperium” section (the regular glossary), you’ll find a brief description of the Bene Gesserit that tells you: that it is “an ancient school of mental and physical training.” But if you flip a few pages to the appendencies, you’ll notice a section called Appendix III: Report on Bene Gesserit Motives and Purposes. Read this for sure! Want to know why they’re trying to breed somebody called the “Kwisatz Haderach?” This section will fully explain their history, and how they came into existence after the Butlerian Jihad.

1. Kwisatz Haderach

In the first Dune novel, whenever someone wonders if Paul Atrieds is “the one” what they’re referring to is the concept of “Kwisatz Haderach.” Analogously, this is a little like the “Chosen One” in Star Wars, and the Dune glossary describes it as “Shortening of the Way,” and “a male Bene Gesserit whose organic mental powers would bridge space and time.” So, kind of like a super-prescient space god, but also a person who could unite various factions. It’s actually no spoiler to tell you that Paul is the Kwisatz Haderach, and that’s because the story isn’t about finding out whether or not that’s true. Instead, it’s all about what happens when Paul becomes the person (or thing) that he’s meant to be. Having this stuff in your head when you watch the new movie or even read the book for the first time, actually make the experience more enjoyable, because you’re not constantly having to flip to the back.

Dune comes to theaters December 18.