NEW YORK — About an hour after downloading TikTok, the popular video-sharing app, I experienced a bizarre sensation, one I haven’t felt in a long time while on the internet. The knot in my chest loosened, my head felt injected with helium, and the corners of my mouth crept upward into a smile.

Was this ... happiness?

TikTok — a quirky hybrid of Snapchat, the defunct video app Vine and the TV segment “Carpool Karaoke” — is a refreshing outlier in the social media universe.

There are no ads. There’s no news, unless you count learning about viral dance crazes. There are few preening Instagram models hawking weight-loss tea, and a distinct lack of crazy uncles posting Infowars clips.

Instead, TikTok — a Chinese-made app that was known as Musical.ly until ByteDance, the Chinese internet conglomerate, acquired the company in 2017 and merged it with a video app it owned — has a simple premise. Users create short videos set to music, often lip-syncing along, dancing or acting out short skits. The app contains templates and visual effects to spice up the videos. There is also a livestreaming feature that allows users to send virtual “gifts” to their favorite creators, which can be bought with real money. The rest works like any other social app — followers, hashtags, likes and comments.

It doesn’t sound like much. But, somehow, it adds up to what might well be the only truly pleasant social network in existence.

I feel comfortable making that call because I go on social networks for a living, and I have spent thousands of hours wading through an unholy slurry of Twitter spammers, Instagram scammers, teenage YouTube fascists, and baby boomers whose brains have been turned to pudding by too many Facebook memes.

TikTok has none of that. Instead, it’s that rarest of internet creatures: a place where people can let down their guards, act silly with their friends and sample the fruits of human creativity without being barraged by abusive trolls or algorithmically amplified misinformation. It’s a throwback to a time before the commercialization of internet influence, when web culture consisted mainly of harmless weirdos trying to make each other laugh.

“It’s a bit of an escape,” said Mr Billy Mann, a TikTok creator who uses the platform to make comedy videos for his more than 650,000 followers.

“It’s a safe haven for people that are seeing the world on fire and being like, ‘I need silliness,' ” he said.

TikTok’s earnest goofiness has turned off some skeptics. But it’s hard to argue with the numbers. The app recently passed 6 million users in the United States, according to a report from the market research firm Sensor Tower.

As of Friday, it ranked No. 4 among free apps in Apple’s app store, ahead of Snapchat, Netflix and Facebook Messenger. Globally, the app, whose Chinese version is called Douyin, had 500 million monthly active users as of July, making it bigger than Twitter and about half the size of Instagram.

Currently, TikTok makes money through virtual gift sales and brand collaborations, such as a Guess-sponsored “fashion takeover.” There are no ads inside the app, although the company’s privacy policy leaves room for them in the future. TikTok, which is privately held, does not disclose financial information, but Sensor Tower estimates that it took in roughly $3.5 million in October.

TikTok’s success has spawned legions of influencers, users with millions of followers and household-name status among teenagers. And it has propelled ByteDance, which also owns a suite of other social media and news apps, to a reported valuation of $75 billion, making it one of the most valuable startups in the world.

TikTok’s global head of marketing, Mr Stefan Heinrich, said in a statement that the company’s mission was to “capture and present the world’s creativity, knowledge and moments that matter, directly from the mobile phone.”

In perhaps the clearest sign that TikTok is on to something, Facebook is trying to kill it. Last month, the company quietly released Lasso, a clunky clone that borrowed many of TikTok’s core features and even tried to siphon off some of its power users. Lasso got off to a slow start, and is now the 687th most downloaded photo and video app in the United States, according to the mobile data company AppAnnie. The executive leading the Lasso team, Mr Brady Voss, left the company shortly after the app was released. (Facebook declined to comment, and Mr Voss did not respond to a request for comment.)

Before I go any further, let’s get one thing out of the way: If you’re reading this, you are almost certainly too old to feel at home on TikTok. The company declined to provide information about its users, but judging from what’s on the platform, the median TikTok user seems to hover in the midteens. TikTok is full of acne-studded faces, barely concealed tween angst and impenetrable youth-culture references. As far as I can tell, there is no way for adults to use it without feeling as if they are chaperoning a high school dance.

Officially, TikTok users must be 13 or older to join. But the age-verification process is easy to circumvent, and while browsing the platform, I stumbled upon several videos starring people who appeared to be much younger. In its previous incarnation as Musical.ly, TikTok drew fire from some privacy advocates, who accused it of pushing the limits of the Children’s Online Privacy Protection Act, a law that prohibits the collection of certain types of information from users younger than 13.

“It’s clearly a really popular, cool site, but you also have the issue of kids being significantly too young for it,” said Mr James P. Steyer, chief executive of Common Sense Media, a nonprofit that reviews tech products for families. “It’s not that the content on TikTok isn’t OK for your 15-year-old. It’s what happens to your 6- or 7-year-old.”

While using TikTok, I never saw examples of bullying or harassment. (Both of which are prohibited by TikTok’s community guidelines, as is sexually explicit content.) There are, however, a decent number of videos featuring teenage girls dancing suggestively — which, if you are a 31-year-old newspaper columnist and not a 16-year-old boy, is fairly unsettling.

A TikTok spokeswoman said in a statement that promoting safety and positivity on the platform is “our top priority.” She added, “We periodically add to and adjust our protective measures, policies and moderation efforts to support the well-being of our users.”

Is TikTok a Facebook killer? No, probably not. For all the variety in its videos, it is still a fairly limited app, with a more narrow appeal than more populist social platforms.

But by purposely limiting its features, by resisting the temptation to monetize its users aggressively and by keeping trolls and bullies off its platform, TikTok has done something truly impressive — it has built a social network that is genuinely fun to use.

There might be a lesson there. THE NEW YORK TIMES