Facebook is rolling out ephemeral stories and messaging in its mobile apps today, bringing the popular format for sharing photos and videos to more than 1.65 billion people a day. The move is part of an all-out effort to blunt the momentum of Snapchat, which invented the stories format in 2013, and to ensure Facebook’s continued dominance in an era where photo and video become a primary mode of communication. Its relative success or failure will go a long way in determining who owns the near future of social networking.

The update rolling out globally this morning on iOS and Android has three parts: a redesigned in-app camera, a new feed of ephemeral stories at the top of the News Feed, and a private messaging feature called Direct. Taken together, the features represent the biggest changes to Facebook’s core product in recent memory.

The company first introduced a clone of Snapchat stories in August with Instagram, reflecting the company’s belief that camera-based messaging represents the future of social interaction. Facebook Messenger was next, and testing began inside Facebook’s flagship app in January. WhatsApp rolled out a version in February.

“The way people create content is changing to be from text to photos and videos,” said Connor Hayes, product manager for Facebook stories. “This is in turn changing the way they’re sharing with one another and interacting online.” He added: “This is something that Snapchat has really pioneered.”

As on Snapchat, Facebook stories consist of photos and images that disappear 24 hours after they are posted. You can decorate your posts with text, drawings, stickers, and Snapchat-like animated filters. While the basic suite of creative tools is the same across Facebook’s products, the flagship app’s stories have a few twists of their own. It’s the first Facebook app to get animated face filters, for example, and the company worked with artists Hattie Stewart and Douglas Coupland to design original filters for the app.

Other changes are more cosmetic — and, in some cases, appear to be different for difference’s sake. Instead of swiping left or right to change filters as on Instagram or Snapchat, for example, you swipe up or down. There’s also a chalk marker in the drawing tools that is unique within Facebook’s family of stories products.

“The way people create content is changing to be from text to photos and videos.”

To create a story, you can either swipe right on the News Feed or tap the camera in the top-left corner of the mobile app. Once you’re satisfied with your creation, you can either share it with all your friends or send it to a subset of friends you select. In the former case, your post will appear in a horizontally scrolling feed of stories that now sits atop the Facebook app. (The feed is ranked by how close Facebook thinks you are to the person who shared it.) In the latter case, the message will appear in “Direct,” a new part of the Facebook app that is roughly equivalent to Instagram’s direct messages.

There are many ways you could think about Facebook’s introduction of stories. Here are a few.

Stories as a milestone in the rise of camera-based communication. Whether or not you accept the idea that image-based messaging will eventually dominate the way we share online, Facebook’s introduction of stories represents an important validation of that concept. It’s also a blow to text-based communication, which has important implications for (among others) publishers, advertisers, and people who have something to say that doesn’t involve a selfie.

Stories as an embrace of your real friends — at least for a while. At launch, Facebook stories are unavailable to brands, publishers, celebrity pages, and advertisers. The idea is to create a more personal, intimate version of the News Feed — the same idea that turned Snapchat into the default mobile communication tool for a younger generation, at least in the United States. Ads are coming, though — Facebook said it has deals with six film studios to make promotional filters on an experimental basis.

An existential threat to Snapchat

Stories as an all-out competitive assault on Snapchat. That Facebook has now brought stories to its entire suite of consumer products represents a powerful validation of Snap’s product genius. It is also an existential threat. Facebook’s entry into live video last year pushed rival products, including Meerkat and Twitter’s Periscope, to the sidelines — and there’s every reason to believe that Facebook’s adoption of stories could have the same effect on Snap. The question is whether Facebook’s global reach is powerful enough to offset the fact that, at least at launch, its version of stories is clumsier than Snap’s (see below).

Stories as a second News Feed. The News Feed is by far Facebook’s most successful and profitable product. That the company would add a second, competitive feed to its app — and to place it on top of the News Feed — is a remarkable change, even if it’s just replicating the approach Facebook took with Instagram stories. It also suggests the still text-heavy News Feed will have to evolve dramatically in years to come. Will the News Feed one day absorb stories? Or will stories absorb it?

Stories as a Facebook Messenger competitor. Facebook went to great lengths in 2014 to separate Messenger from its flagship app, to the howls of many users. With stories, Facebook is introducing Direct — an in-app messenger tied to its new ephemeral messages. Facebook likens it to a comment thread, but it works just as well for sending normal messages. Over time, I wonder if it won’t chip away at the usage Messenger — which launched a notably clunky version of stories of its own just days ago.

Stories as a chore. Where should you post your daily story now becomes a daily concern for a certain subset of youngish, social media-savvy people. Facebook says stories belong everywhere that people are talking online, but what if the format is a fad? And what if forcing it on users across its entire family of app leads to a general fatigue with the idea? The company says each of its apps has a distinctive audience, and I believe it. But there’s also plenty of overlap. There’s a risk here that Facebook’s mania for stories will be interpreted as overkill by its users, and the feature will ultimately fade into the background. (This happened with live video!)

There’s every reason to believe Facebook stories will succeed

Whatever you think of Facebook stories, there’s every reason to believe it will succeed. The company is so large that its features often seem to succeed by default — Facebook’s “save for later” button, a halfhearted competitor to Pocket and Instapaper, last year reached an astounding 250 million users a month. When Facebook says that the camera will be at the center of our communication in the future, we should take it seriously — in part because by its sheer scale, the company can simply decide that the camera is the future.

Still, doubts creep in. When you go to share a story using the new Facebook camera, the default suggested place to share is the regular, permanent News Feed — a product decision that seems to undermine the entire point of a wild and wacky camera built to encourage ephemeral sharing. It underscores the idea that Facebook has little understanding of what drives us to share outside what its endless Excel spreadsheets of data suggest — an idea reinforced by a moment Monday when a company art director told reporters that a promotional Minions filter was created “to really celebrate fandom and create community around entertainment vehicles that people celebrate together.” (The filter is an advertisement.)

Ultimately, Facebook stories face the same basic challenge that the larger News Feed does — context collapse, or the idea that sharing something with everyone you know discourages sharing generally. It’s the reason that original sharing on Facebook is said to have declined: when you know that anything you post might be seen by your boss and your mom and your ex, you often choose not to share at all.

Making your posts ephemeral means that, in most cases, they won’t come back to haunt you. But that same unpredictable set of eyes is still on them, even if temporarily, watching you on Facebook from every corner of your life. And that may prove to be something that no filter or drawing tool, no matter how delightful, can overcome.