It’s not quite anonymous, but forums standalone app Rooms is Facebook’s first product that allows you to ditch your real name. Rooms lets you set up a mobile-only in-app discussion space about any topic, customize the look and moderation settings, set a screen name for the room, and choose who to invite to share text, photos, videos, and comments with others in the Room. It’s a bit like forums inside an Instagram-style vertical feed. Rooms doesn’t require a Facebook account or even an email address to sign up. It employs an innovative QR-code invite system where people take a photo or screenshot of a Room’s code to gain entry.

Rooms lets you share things that might not fit in the News Feeds of your friends, from nerdy niche culture topics to serious discussions about health or other sensitive subjects.

The New York Times reported earlier this month that Facebook was launching an app that allowed anonymity, which isn’t exactly right, but Rooms does allow people to discuss topics in forum-like spaces as the Times wrote.

Rooms was built by Josh Miller and his team from Branch, which Facebook acquired in January.

(Read my Q&A with Miller for more insight into how Rooms was modeled after the early Internet, with its distinct spaces, customization, and option to call yourself whatever you want.)

Miller brushed off comparisons to other apps, saying “Secret and Yik Yak are very different products” than Rooms. Rather than being a clone of something like Secret, Rooms could host a global forum similar to Secret where people share revelations and don’t include any clue to their real name. But it could also host disease support groups, book clubs, politics discussions, enthusiast communities for sports or tech products, or giant collaborative feeds dedicated to certain types of art or poetry.

The standalone app from Facebook’s Creative Labs initiative follows newsreader Paper and ephemeral messaging app Slingshot. neither of those has seen blockbuster traffic, but that hasn’t stopped Facebook from growing the Creative Labs project to test out different social app experiences without messing with its main app.

Where Rooms is truly different from Facebook is that it doesn’t import your social graph from either your phone’s contacts, Facebook, or anywhere else. Its invite system is designed to make you build a community based on interest instead.

Each Room gets a unique QR Code that can be shared with whoever its creator and members want to join them. That could mean keeping it super-private to just a few others interested in the topic, posting it publicly so anyone can join, or printing it out so people in a specific geographic area in the real world can add themselves. There is the issue that members could share the invite QR code or publicly post it without permission, blowing up a Room.

To keep trolls from overrunning Rooms, moderators can ban anyone, and their device will be permanently banned from rejoining. Facebook will also be applying its standard community guidelines to content on Rooms. So, if something is flagged for hate speech, bullying, threats, spam, nudity, or other disruptive behavior, Facebook can unilaterally delete posts, ban members, or even take down entire Rooms.

In that way, the app strongly differs from the early web, which was more of an “anything goes” wild west. That could be considered a limitation on free speech, but Miller believes it’s the only way to keep Rooms from devolving into a dangerous cess pool of hatred.

Moderators have more control over the room, beyond just banning unruly users. They can also set a nickname for their room, add a background image and even select an emoji that room members can use in place of the “Like” button on posts. For example, a Room for a Farmer’s Market in the city might choose to use a Strawberry emoji instead of a Like button.

Moderators can also make rooms 18+, in order to host rooms with topics not fit for minors. (However, it’s worth pointing out that users only have to say “Yes, I’m over 18” to get in – there’s no actual check.)

Users can optionally associate an email address with their Rooms account, so if they lose their phone or change devices they would have a way to recover that account, if need be. But this is not required.

At launch, there will be no native discovery tool for finding Rooms, which means you’ll have to get invite codes from other people in order to get in – a move which could potentially limit early adoption. Eventually, Miller’s team may add Room suggestions to the product. That’s why it’s asking Room creators if they want to turn on discoverability.

Explains Miller, Mark Zuckerberg and Facebook Chief Product Officer Chris Cox asked him how he was going to make sure people’s Rooms didn’t get overwhelmed with new members too quickly, and this was the result.

The Rooms team is also now accepting applications at teams@rooms.me from Room creators who want to help with community growth.

Miller says he won’t judge Rooms based on user count. In fact, he purposefully wants it to grow slow rather than have people’s Rooms suddenly swell with members and become diluted or unintelligible. Instead, he’s hoping the app finds some obsessively loyal users who come back every day to discuss important topics to them.

Not even Miller can foresee exactly what will happen with Rooms. He tells me, “I think the coolest rooms will be things we haven’t thought of yet. The Twitter guys didn’t know what Twitter would be good for. The Snapchat guys didn’t know what Snapchat would be good for.”

If Rooms fails, it will have taught Facebook a lesson about micro-sharing that it could use to inform its News Feed and Groups products. But if it succeeds, it could spawn wide-reaching, active communities that could never live on Facebook.

Rooms is iOS-only at launch, and is available in the U.S., U.K. and a few other English-speaking countries. An Android version is tentatively planned for early 2015.

Additional reporting: Sarah Perez