MENLO PARK, Calif. >> Mark Zuckerberg declared in March that he planned to shift Facebook away from being a public town square and to private communications. Now the chief executive is rolling out the first in a series of changes to achieve that.

On today, at its annual developer conference, Facebook unveiled a redesign of its mobile app and desktop site. The revisions add new features to promote group-based communications instead of News Feed, where people publicly post a cascade of messages and status updates.

With the changes, users can more easily message one another and share news and other items with members of private groups on the site, the company said. Zuckerberg is working to integrate and encrypt Facebook’s different messaging services, which include WhatsApp and Messenger. The company also plans to continue emphasizing its Stories product, which allows people to post updates that disappear after 24 hours. And it unveiled a spare, stark white look for Facebook, a departure from the site’s largely blue-tinted design.

The features, when combined, “will end up creating a more trustworthy platform,” Zuckerberg said in an interview. “Everywhere you can see and connect with friends, you’ll be able to see and connect with groups; it’s going to be woven into the fabric of Facebook.”

The redesign is the most tangible sign of how the privacy scandals and user-data issues that have roiled Facebook are forcing change at the company. The social network has spent the past three years grappling with criticism that it did not properly protect its users’ information; that it spread false news and other toxic content, and that it was used as a tool for election interference. Last week, it said it expected to be fined up to $5 billion by the Federal Trade Commission for privacy violations, in what would be a record penalty against a technology company by the United States.

Facebook is also playing catch-up with people’s shifting social media behavior. Questions about the benefits of social media and more recognition of its ills have prompted many to turn toward methods of private communications, such as messaging apps.

“By far, the three fastest-growing areas of online communication are private messaging, groups and Stories,” Zuckerberg said. “In 2019, we expect the amount of Stories that are shared to outnumber the amount of Feed posts that are shared.”

Eventually, he said, Facebook plans to roll out dozens of small product updates across its four main apps of WhatsApp, Instagram, Messenger and Facebook.

The shift raises questions for Facebook, including how it will make money from private communications. The company generates most of its $56 billion in annual revenue from targeted advertising that is based partly on what people publicly post about themselves.

“The challenge of steering the Facebook ship in this new, private direction is going to be massive,” said Debra Aho Williamson, an internet analyst at eMarketer, a research firm. “And it leaves a lot of questions unaddressed, in particular how this shift will affect its equally massive advertising business.”

Marc Rotenberg, president of the Electronic Privacy Information Center, an internet industry think tank, said the changes were late given that privacy concerns “were raised many, many years ago” to Facebook.

The initial new features that were unveiled today alter the site but do not amount to a full-scale overhaul. Facebook is adding a Groups tab to its main mobile app and desktop menus, for example. Recommendations for groups that users may want to join will pop up in various areas of the app. Messages meant for close friends and family will have their own section inside Facebook Messenger. All in all, it will be hard for someone to open up Facebook and not see a prompt beckoning them to a group chat.

Facebook also revealed other changes. It plans to roll out its Dating feature to more than a dozen new countries, such as Thailand and Canada; the service is not available in the United States. Instagram introduced new digital shopping and commerce features inside the app.

And Facebook’s Craigslist competitor, called Marketplace, integrated shipping and payment capabilities for the first time. It allows people to pay for and ship items they have purchased from other Facebook users anywhere within the continental United States. Previously, users were required to arrange payment privately, off Facebook.

The focus on Facebook Groups is convenient for the company because it reduces the amount of public content that it has to moderate and ultimately answer for, said Jennifer Grygiel, an assistant professor of media and communication at the Newhouse School at Syracuse University. “I think it’s a way for them to offload responsibility,” the professor said.

Facebook’s developer conference, called F8, began in 2007 to entice developers to build apps for the social network. The company offered developers access to its so-called social graph, its rich web of user connections and personal data.

Last year, The New York Times and others revealed that Cambridge Analytica, a British political firm with developer access to Facebook’s social graph, had harvested the personal information of millions of Facebook users without their consent, in order to build voter profiles for the Trump presidential campaign. That revelation brought heightened scrutiny to the social giant, particularly on how it handled users’ information.

Facebook has since vowed to supervise its users’ information more closely and placed greater restrictions on developer access. That makes this year’s F8 more challenging for developers who have relied on the social network’s data.

“It’s going to make developing for the platform harder for a lot of these folks,” Zuckerberg said. He added that any short-term difficulties for developers were worth the long-term benefit of greater user trust in the platform.

The new privacy direction may create other issues. Closed groups and encrypted services will make it more difficult to identify and root out dangerous or abusive behavior, Zuckerberg said, though he added the company’s automated systems have ways of detecting illicit activities — like examining traffic patterns — without scanning the content of private messages.

“There’s still a lot more to do,” he said, adding that the spotlight on the company had “definitely prompted more introspection around what direction our services should go in.”

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