A PROPER SEX MANUAL is more than just a set of instructions. To be any use at all, a book about sex needs to help you reimagine your body and how it relates to other people’s bodies. And because so much of sexuality is bound up with identity and culture, a really useful sex manual is also an incitement to cast off your crappy old ways of thinking about selfhood. In fact, any sex manual worth its salt is an instrument of liberation.

Allison Moon’s Girl Sex 101 is a fantastic sex primer, one which shows how far we’ve progressed in thinking about sexuality and gender — and which prods us gently to make even more progress than that. Girl Sex 101 is aimed at “ladies and lady-lovers of all genders and orientations” with a specific focus on women who have sex with women. But it’s a must-read for absolutely anybody who has sex involving female bodies.

What makes Girl Sex 101 such a brilliant book is that it’s not simply process-oriented or task-oriented. Given widespread ignorance about women’s bodies, even a book that simply offered accurate and detailed information about female sexuality would have been amazing to put into people’s hands. Moon, however, doesn’t treat sexuality as purely a matter of bodies; she treats sex as something that happens between people, with all their complex humanity. That makes this book a guide not just to satisfying sex, but to becoming a better lover in general.

Part of the book’s success is the careful structure of Girl Sex 101, which starts out with flirting and works its way up to actual sex acts. The first two chapters focus on the stuff that happens before sex, including finding and negotiating with a lover, and this allows Moon to create foundations that the rest of the book rests on. The structure of the book then mirrors the progression of a sexual encounter and parallels this with the reader’s own individual progress in discovering her own sexuality. As Moon gets deeper into the wilds of sex between (or involving) women, she also offers more and more advanced insights on knowing yourself and understanding your own sexuality. By the time we get to the second-to-last section, which is all about figuring out your own identity, the reading experience feels like an arrival on several levels. (The “101” in the title is an intentional pun, by the way, with the book structured as both a road trip on Highway 101 and as an introductory text.)

Like a lot of the best sex and relationship manuals from years past — like The Ethical Slut or The Good Vibrations Guide to Sex — Girl Sex 101 is as much about giving permission as it is about providing instructions. Moon is relentlessly sex-positive and body-positive, giving the reader encouragement to enjoy whatever they enjoy and to feel however they feel. Moon’s narrator exhorts the reader to try to have an “embodied yes,” one which feels grounded inside your body. She asks, “What does ‘yes’ feel like? Excited? Energized? Warm? Curious?” (And there’s also permission/encouragement to say “no” if something doesn’t feel right.)

Every sex manual is a product of its time. Back in the early 1970s, Alex Comfort’s The Joy of Sex was a massively popular manifestation of the Sexual Revolution, promising that people could seek pleasure in any way that made sense to them. Its groovy ’70s artwork and cavalier attitudes toward rape, disability, and sexually transmitted diseases seem horribly outdated now, but in 1972 it was an eye-opener, giving people their first ideas about how to explore a diversity of sexual attitudes and practices. Comfort had previously written a novel about sexual liberation and non-monogamy, 1961’s Come Out to Play (which contains one terrific line, where the female love interest agrees to non-monogamy with the main character by saying, “I don’t care about forsaking all others, but don’t forsake me”). Come Out to Play is a seriously loopy book that contains a lot of quirky humor alongside sexual mores that would seem outré now, and it must have seemed outlandish in 1961. But Comfort’s novel didn’t succeed in influencing sexual attitudes in the same way that his nonfiction book about how to have great sex managed to. There’s just something about a sex manual that’s authoritative and reassuring; it allows people to take on new attitudes and discard the hang-ups that they’ve inherited from previous generations.

Girl Sex 101, like The Joy of Sex, is very much a product of its time — something that Moon acknowledges in the book’s foreword. This book has the conversational feel of social media, with short sections written by outside contributors and lots of fun pop-up sections. It also feels like a product of 2015’s conversations about inclusion and privilege (including racism, ableism, transphobia, and other issues that feminism has often overlooked) in a very thoughtful way.

In particular, Girl Sex 101 makes an admirable effort to include people whose bodies aren’t usually included in discussions of sexuality (particularly female sexuality). Most noticeably, transgender, genderqueer, and intersex people are included in every section of the book, and this is part of an effort to include other types of often-marginalized bodies, including disabled people and seniors. Moon doesn’t fall into the trap of carving out a special chapter for trans people or people with disabilities; instead, she integrates them into the text at every turn. At one point, for example, she’s discussing how to play with the chest of a male-to-female transsexual who’s had top surgery, and then she transitions seamlessly into saying “new moms usually lactate,” because these are just slightly different cases that need to be considered. During another part of the book, she discusses vaginal play for transwomen who’ve had bottom surgery immediately before moving on to women who’ve been through menopause.

One crucial message of Girl Sex 101 is that female sexuality needs to be defined more inclusively — girls are a category that, in 2015, includes a lot of outliers. “Bodies are cool, and so are people,” writes Moon in the middle of a frank section about the fact that some girls do have penises. And at the same time, she is constantly aware of how bodies vary, and she provides practical advice for bodies of different sizes and shapes so that people don’t just avoid body shame, but actually get a positive sense of their bodies.

Equally as revolutionary as her focus on inclusion is the clarity with which Moon lays out the basics of sex — both the mechanics and the emotional intricacies. Every other page of this 370-page book contains neat tips and tricks on how to be a better lover, from ergonomics (“the 100% biological wrist-brace”) to how to be a good “top” and pay attention to the signals you’re receiving from your partner. There are fantastic explanations of how to use sex toys, from strap-ons to anal toys, and a very thorough and informative section on sexually transmitted diseases.

Above all, Girl Sex 101 manages to be “sex-positive” without being unrealistic about human nature. Every step along the way, Moon recognizes just how hard it is for most people to communicate and how challenging good boundaries can be even for the most well-intentioned. Moon and her collaborators don’t assume that casting off your sexual hang-ups will turn you into some kind of brilliant emotional savant who traverses every situation with total aplomb. In general, this book has an approach to consent and communication that feels revolutionary, even in 2015 — with an emphasis on not just giving clear consent, but on avoiding passive-aggressiveness and random emotional baggage while expressing your needs, desires, and dislikes. It’s both refreshing and kind of thrilling.

Meanwhile, though, Moon includes a serialized piece of fiction about a road trip in every chapter, and this didn’t entirely work for me. Bits of the story, about a video artist and her friends, were charming and sweet, but at times it just distracted me because it felt somewhat extraneous, and the characters didn’t feel distinctive enough for me to keep track of them all. Also, the book’s illustrations by KD Diamond are often cute, but occasionally they seemed a little too cartoony — and they also seemed like exactly the thing that might date this book faster than anything else.

All in all, though, Girl Sex 101 is a book that both sexual neophytes and sex savants will find indispensable. It’s full of not just useful information and tips, but new ways of looking at sexuality and relationships, and it feels like the sex manual that we needed to have in 2015. This is one of those books that will make you look at not just your lover, but yourself, differently, after you read it.

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Charlie Jane Anders is the author of All the Birds in the Sky, a novel coming in early 2016 from Tor Books.