How the World Got Wired · The Other Internet

The Algorithm That Reads You

The app is called TikTok. It is owned by a Chinese company called ByteDance.

ByteDance was founded in 2012, in Beijing, by a young Chinese engineer named Zhang Yiming. He was thirty years old. Like Mark Zuckerberg in his Harvard dorm, like Larry Page in his Stanford lab, he had been thinking carefully about how people use the internet, and he had noticed something the American companies had not quite figured out.

The American social networks, you remember from the last chapter, were built around the social graph — the map of who knows whom. Facebook showed you what your friends were doing. Instagram showed you the photos of accounts you had chosen to follow. Twitter showed you the posts of people you had chosen to listen to. These were networks of people you already knew about.

Zhang Yiming’s idea was different. What if the app didn’t care who you knew at all? What if, instead, the app showed you a stream of videos chosen by an extraordinarily clever computer program — an algorithm — that watched, with great care, what you actually paid attention to? You wouldn’t have to follow anyone. You wouldn’t have to choose anything. You would just open the app, and it would start showing you videos. If you watched a video to the end, the algorithm noticed. If you swiped past it after one second, the algorithm noticed that too. If you replayed something, the algorithm noticed. If you commented, or shared, or paused, the algorithm noticed. Within a few hundred videos — a process that could take a new user about an hour — the algorithm would have built a very precise model of what kept that particular human’s eyes on the screen. From then on, it would just keep feeding them more of what worked.

ByteDance launched this app in China, in 2016. They called it Douyin. The next year, they launched an international version, in English, called TikTok. In 2018, they bought a smaller American app called Musical.ly and merged it into TikTok.

What happened next was unprecedented in the history of social media. By 2021, TikTok had passed one billion monthly users. By 2024, it was the most-downloaded app in the world, several years running. The average teenager in countries where TikTok is popular spends a significant fraction of their waking life watching its videos — often, by their own admission, more than they want to.

The reason is the algorithm. TikTok’s algorithm turns out to be extraordinarily good at finding videos that hold each person’s attention. Inside the industry, people who study this kind of thing have written reports trying to explain why TikTok is so much more engaging than Facebook or Instagram. The simplest answer is: TikTok’s algorithm was designed, from the very beginning, to do nothing else. It does not have to worry about your friends. It does not have to worry about the social graph. It just has to keep your eyes on the screen. And it is very, very good at that.

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