On a recent afternoon, Adam Mosseri, the head of Instagram, assembled members of his staff to discuss the secret details of a critical project: the elimination of public “likes.” You’ll be able to see how many hearts your posts get, dear user, but not other people’s tallies. The effort is referred to internally as “Project Daisy” — as in “Does she love me? Or love me not?”

Likes are the social media currency undergirding an entire influencer economy, inspiring a million Kardashian wannabes and giving many of us regular people daily endorphin hits. But lately, Mr. Mosseri has been concerned about the unanticipated consequences of Instagram as approval arbiter.

He kept thinking about an episode of “Black Mirror,” the British dystopian anthology series, in which the characters rate everyone they interact with on a scale of 1 to 5 stars. (It doesn’t end well.)

Mr. Mosseri knows something about dealing with dystopian tech fallout. He came to Instagram in October 2018 after years overseeing the Facebook News Feed, an unwitting engine of fake news, inflammatory rhetoric and disinformation. He wants to avoid similar pitfalls at Instagram, which is owned by Facebook.

But making likes private will be a major shift for Instagram’s more than 1 billion users, for whom daily assessment of one another’s popularity has become like breathing.

And so the company is carefully considering how this will happen, for months “dog-fooding” (internal Insta-talk for testing) different variations of the new format. A post’s achievement of “thousands of likes” or “tens of thousands of likes” might still be public. Users might be still be able to find others’ likes with a little more digging in the app. But the average teenager under pressure to be popular won’t need to suffer the indignity of only his mom liking his skateboarding post.

Mr. Mosseri sees Project Daisy, which the company intends to introduce early this year, as a signal to the world that he has learned from Facebook’s mistakes and is thinking about the larger, potentially corrosive impact of social media.

“We should have started to more proactively think about how Instagram and Facebook could be abused and mitigate those risks,” he said. “We’re playing catch-up.”

In the meeting, he asked his team: “How do we depressurize the app?” Brands would still need to count likes for their advertising, so what would that look like? Nobody wanted to break up the “BeyHive” (Beyoncé’s 136.7 million followers) or upset a major influencer like Selena Gomez (144 million), but does that mean the average popular teenager with 1,000 followers will see a similar display? How would users outside the United States respond? At one point, Mr. Mosseri stopped a designer and asked, “But how would that look in other languages?”

Then, he exhaled, stretched his arms behind his head and said, “I just don’t want to piss anyone off.”

By then, I had spent several afternoons with Mr. Mosseri, and his concern struck me as the best encapsulation of his fascinating, sometimes fraught tenure at Instagram. The man who is working to mostly eliminate likes really wants to be liked.

The Selfie Factory

Mr. Mosseri is a close confidant of Facebook’s chief executive, Mark Zuckerberg, and he knows that his installment at Instagram was met with widespread skepticism among its staff, seen as evidence that the blue, squaresville platform had officially swallowed the chic rainbow-colored one.

For years, Instagram had tried to maintain at least the appearance of independence from Facebook, which acquired it for $1 billion in 2012. Then Instagram’s founders, Kevin Systrom and Mike Krieger, clashed with Mr. Zuckerberg, and departed.

Dozens of employees also left. Two separately functioning teams of engineers and product managers were combined. Instagram had even changed its name to “Instagram from Facebook” — appalling many of the influencers who wouldn’t be caught dead on Facebook, which for them had become the realm of cantankerous uncles venting about politics and random high school friends posting reunion photos.

When Mr. Mosseri was introduced as Instagram’s new leader at a question-and-answer session with employees, someone asked, in effect, “Why are you making the head of Instagram someone who failed at Facebook’s News Feed?” according to a person who attended the meeting.

“It was a huge emotional event when Kevin and Mike left. So there was definitely skepticism about me stepping into the role,” Mr. Mosseri told me.

Concerns spread beyond Instagram’s corporate walls to its most obsessive users. Would the relationship with Facebook taint the app that had transformed the way we take pictures and turned an entire generation into selfie-taking machines?

This past fall, Mr. Zuckerberg, two days after he was grilled by Congress about Facebook’s handling of user data, political advertising, disinformation and child pornography, stopped by Instagram’s offices. Mr. Mosseri posted a selfie with his arm around him. “Mark stopped by Instagram!” Instagram users weighed in: “Instagram has lost its way” and “Instagram is dead.” and “Make Instagram great again.”

But while Mr. Zuckerberg has been cast by critics as defensive and closed off to criticism and the news media, Mr. Mosseri, 36, projects the opposite. He’s affable and easygoing, exuding the laid-back intensity of a Bay Area tech executive who was born in the East Village. He is accessible to the news media, and unafraid of the occasional Twitter war with the acerbic tech columnist Kara Swisher (a contributing opinion writer for The New York Times). He posts an endless stream of relatable photos of his young sons (#DadLife). And he does regular “ask me anything” sessions.

This charm offensive, combined with Mr. Mosseri’s efforts to stop bullying, remove photos of self-harm and other safety and integrity measures that Facebook may have been late to, has won him respect. But it has not quieted the larger concerns about the mother ship.

“There’s more anxiety now just about, ‘What is our place within the broader company? How do we relate to Facebook? How do we relate to WhatsApp?’ It’s less anxiety around me,” Mr. Mosseri said. Then he added, “But I just want to be careful about blind spots here, because if there was a lot of anxiety about me, maybe they wouldn’t tell me.”

Instagram has revolutionized shopping, dealt a near-death blow to women’s magazines, taken celebrities from TV and movie screens to our fingertips and made Shih Tzus and personal trainers household names, (At least in some households.) To discuss the photo-sharing app’s future, Mr. Mosseri and I sat, among other places, in the sunny food court in its New York headquarters, in a building that once housed a Wanamaker’s department store and also includes the Facebook offices.

Designed to share everything, the company makes certain that visitors to its base of operations don’t share anything, asking most members of the news media who are granted access to sign nondisclosure agreements. (Mine was waived.) The white loft-like space is a sort of Willy Wonka chocolate factory of social media, with selfie-ready backdrops at every turn. There is an iridescent beehive-like installation, a complimentary gelato and biscotti bar, and a rotating wall of posts from @shop, Instagram’s latest effort to bring in small businesses.

Instagram’s worldwide staff totals more than 1,000, and even as Mr. Mosseri tried to convince them that he is not just a “Facebook guy,” he must also convince Mr. Zuckerberg and Facebook that his decisions will benefit the parent company.

The way Facebook executives see it, Instagram would not have become so ubiquitous and beloved if it had not siphoned users and support from Facebook. Now, with Mr. Mosseri leading the charge, it is time for Instagram, the company’s fastest-growing asset, to give back.

“There is this misperception about the journey that Instagram has been on since Facebook acquired it,” said Justin Osofsky, a longtime senior Facebook executive who is now the chief operating officer of Instagram. “There was this narrative that it was a team of 13 people and the start-up journey led to an inevitable outcome for Instagram, when I believe Facebook played an incredibly important role in its growth.”

In an email, Mr. Zuckerberg said Instagram’s founders had “created something special, and the team has taken that and helped build it into something that people around the world love.” But, he added, “we still have a lot to do to make the experience even better and make sure we’re living up to what people expect from us.”

This delicate balance — keeping both Facebook and Instagram happy and facing animosity in both camps — reminded Mr. Mosseri of his father, an Israeli-American psychotherapist who speaks Hebrew with an American accent and English with an Israeli accent.

“I feel like I speak two languages and neither is perfect,” Mr. Mosseri said. “It’s like, either place you go you get, ‘Where are you from?’”

Jogs With Zuck

Mr. Mosseri’s story began like those of many tech executives: in college. He was a freshman at N.Y.U. when he started designing websites, mostly to help pay the rent on the windowless room in the one-bathroom apartment that he shared with five roommates. He started a small web-design firm with a partner, Sidney Blank, who described it as “two guys with a couple employees futzing around.”

Mr. Mosseri’s firm got a couple of commissions from Brown University and the Architectural League of New York (his mother is an architect), including one to create an interactive rendering of what a redesigned World Trade Center might look like. In 2005, he opened a West Coast office, following a couple of friends to pursue start-up riches in San Francisco.

There, he created Boombox, a music-sharing app. Before he received a cease-and-desist order from the Recording Industry Association of America, the app caught Facebook’s eye. Mr. Mosseri’s wife, Monica, was working at Facebook in operations; Mr. Mosseri had applied there several times but never got an interview. Now, as the company eyed music sharing, he had an in.

In 2008, Mr. Mosseri joined Facebook’s design team, commiting so completely that he’d sometimes crash on a sofa in Silicon Valley with other early Facebook executives rather than go home. Thinking like a designer but coding like an engineer, he embodied the work-hard-play-hard ethos that Facebook looked for in its employees at the time, said Soleio Cuervo, a former product designer at Facebook.

“Facebook has this stigma of being traditional Silicon Valley nerds,” Mr. Cuervo said. “But I actually think it’s a very social culture. Adam played on our code soccer team.”

Like many other early Facebook employees, Mr. Mosseri got close to Mr. Zuckerberg. They occupy similar social circles, they have children who are about the same age and they occasionally go on morning runs together. Mr. Zuckerberg eventually entrusted Mr. Mosseri with overseeing the News Feed, the stream of links, photos and miscellaneous rants that Facebook’s more than two billion users post in more than 100 languages.

Revelations that Russian trolls had meddled to help elect President Trump in 2016, and that the News Feed had been used to spread disinformation during the campaign, set off a series of congressional investigations into Facebook’s practices. Social media, which had been designed to bring us together, had become the ultimate tool for tearing us apart.

Publicly, the blowback landed on Mr. Zuckerberg, but internally it was Mr. Mosseri who had to provide many of the answers. He spent the months after the 2016 election fielding questions about how this happened and how he could make sure it would not happen again.

“I was going around the world, talking to a lot of very harsh critics of us, trying to sift through all the noise and find the signal and figure out how to address these issues and help steer the ship,” Mr. Mosseri said.

The Bully Filter

Even as criticism of Facebook reverberated and younger users in the United States, in particular, abandoned it, Instagram maintained its image as a safe space to share photos of first birthdays and avocado toast.

Facebook purchased Instagram in 2012, when it had 30 million users, and treated it largely as a side project, albeit a profitable one. But Instagram grew faster than anyone had expected. It shrewdly mimicked its rival, Snapchat, introducing the widely popular video-sharing Stories feature, whose private tallying of “watches” has informed Project Daisy.

Users who may have felt their privacy was compromised on Facebook used Instagram to exchange direct messages and share personal moments. In 2018, Instagram’s net advertising revenue in the United States reached nearly $6 billion, a 70 percent increase from the previous year, according to eMarketer, a social media research company.

No longer the quirky stepchild with bunny-ear filters, Instagram has become the future of Facebook in the United States, according to industry analysts who estimate that it is Facebook’s most lucrative asset and arguably one of the best acquisitions in tech history.

“There is this role reversal in Instagram’s metamorphosis from this tiny thing on the side to being the core platform,” said Venky Ganesan, a managing director at Menlo Ventures, a venture capital firm. “The actual Facebook that we know and love — or know and no longer love — is becoming a relic of the past.”

Mr. Zuckerberg began looking at the overall picture of Instagram, WhatsApp and Facebook, or what he calls the “family of apps.” Facebook could seem like a jealous sibling: removing the Instagram logo from its bookmarks menu, for instance, and cutting the traffic that flowed from its platform to Instagram. Instagram users also had an option to cross-post Stories on Facebook, like sharing graham crackers.

Months before Instagram’s founders left, Jan Koum resigned from WhatsApp, the messaging app he co-founded, and from Facebook’s board, amid debates about the amount of user data Facebook had collected from its users.

Mr. Zuckerberg installed Mr. Mosseri as head of product at Instagram, a move that further convinced its founders, Mr. Systrom and Mr. Krieger, that the app they created was increasingly under Mr. Zuckerberg’s control. Not long after, they announced they would depart, leaving tumult in their wake. “No one ever leaves a job because everything’s awesome,” Mr. Systrom told Recode.

Mr. Mosseri had to assemble an almost entirely new leadership team at Instagram, installing several Facebook executives in senior roles. He encouraged previously disparate teams that worked on well-being and integrity to collaborate more closely, overseeing, among other things, efforts to make sure harmful posts were promptly taken down.

“We were doing too much on our own and not enough leveraging of all the work that comes from the much larger team at Facebook,” Mr. Mosseri said.

Though Instagram was largely insulated from criticism after the 2016 election, two reports, prepared by independent groups and released last year by the Senate Intelligence Committee, found that Instagram had since become a favored tool of Russian internet trolls who sought to sow distrust in the American political system. Their tactics included the creation of fake accounts with hundreds of thousands of followers that targeted African-Americans, anti-immigration activists and gun-rights supporters, among others. The app could prove ripe for further interference ahead of the 2020 election.

“From my experiences on the Facebook side, I could try to mitigate some of those risks,” Mr. Mosseri said. Always quick to break the tension, he jokes about the heated conversations he has had with his liberal East Coast relatives about Facebook’s role in Mr. Trump’s victory, but it’s also cause for introspection. “I try to step back and look at things as effectively as we can and be honest about where we made mistakes,” he said. “I’ve asked myself so many times, if I could go back to 2015 or 2016 and give myself a bunch of advice, what advice would I give myself?”

He also echoed the wider thinking within Facebook that Mr. Trump had simply used the platform more effectively than the competition. “Trump used Facebook really well as an advertiser, so I am sure that helped,” he said.

Mr. Mosseri likes to say that “technology isn’t good or bad, it just is.” But how could he be so sure? No one really knows what the long-term sociological impact of Instagram will be; it’s too new. “Social media, I think, often serves as a great amplifier of good and bad,” Mr. Mosseri said.

In other words, social media is sometimes a cesspool because humanity is sometimes a cesspool. And yet it is Mr. Mosseri’s job to make sure the slime doesn’t overtake the subway (to invoke “Ghostbusters”). Instagram is still widely beloved in the United States, but users in Britain largely turned on the platform following reports that graphic images of self-harm on its app might have influenced a 14-year-old girl to commit suicide.

Mr. Mosseri quickly banned such images and ordered the development of additional tools to help users to avoid bullying. As I was writing this article, Mr. Mosseri emailed to say that he wanted to prioritize “well-being focus areas” for Instagram’s teenage users, “including problematic use and loneliness.”

Indeed, the most obvious dark forces — pornography, self-harm, disinformation — seem almost simple compared to the largely unknown long-term impact of a platform that has turned every vacation, every dinner party, every parental milestone into an online performance. Instagram has so incentivized the distortion of reality that it lured moneyed millennials to the doomed Fyre music festival on an impoverished island; a couple fell to their deaths while trying to snap the perfect cliff-side selfie, and a woman vented that her 6-year-old son wasn’t as popular as his siblings because images of him received fewer likes.

Eva Chen, the director of fashion at Instagram, stressed that the app is an accessory for the majority of its users and not the main event. “So much of the advice I give to young people is not even within the confines or constructs of Instagram,” she said. “Living a life to someone else’s standards of what cool is is not a good way to live.”

But what happens when a technology puts the idea of cool in the palm of our hand, tantalizing and taunting us at all hours?

“There are plenty of well-documented reasons to distrust Instagram — the platform where one is never not branding, never not making Facebook money, never not giving Facebook one’s data,” Tavi Gevinson, who became one of the earliest influencers after starting a popular style blog when she was 12, wrote in New York magazine. “But most unnerving are the ways in which it has led me to distrust myself.”

Mr. Osofsky, Instagram’s chief operating officer, pointed to Project Daisy as one example of how seriously he the company’s leaders take the app’s unintended consequences. “We are willing to question and analyze some of the most core aspects of the service when you think about the next decade of Instagram,” he said.

Mr. Mosseri got more philosophical.

“Can I get a little nerdy on you for a second?” I said yes, without reminding him that we’d already talked extensively about “variants” and “ad hoc qualitative research.”

“With a new medium, it starts with euphoria and then goes to hysteria and then hopefully you get some kind of balance,” he said. “It happened with the radio. This happened with TV. There was a huge amount of skepticism about reading Plato because he was writing and no one could argue versus yelling into a public square.”

That means that if Instagram were a Model T Ford, Mr. Mosseri is overseeing a period when he will have to start installing seatbelts and airbags and other safety features.

“It’s very natural for there to be strong skepticism,” he said. “But I do think we create a lot of good in the world.”