How does TikTok's algorithm work?

TikTok's content recommendation system is under scrutiny again after its parent company, ByteDance, agreed to hand control of the app's US operations to a new joint venture including Oracle.

The algorithm is considered the main engine behind the platform's global popularity. But what is so special about it? A recent Reuters report breaks down a few key findings.

What makes the algorithm powerful?

Analysts have said that it is not just the algorithms, but also how they work with the short-video format, that have made TikTok so successful globally.

But TikTok showed that an algorithm, driven by the understanding of a user's interest, could be more powerful. Rather than building its algorithm on a "social graph" like Meta has, TikTok executives have said that its algorithm is based on "interest signals".

The short-video format enables TikTok's algorithm to become much more dynamic and even capable of tracking changes in users' preferences and interests across time, going as granular as what a user may like during a certain period of time during the day.

And the positioning of TikTok as an app built for mobile devices from the beginning also gave it an advantage over rival platforms that had to adapt their interfaces from computer screens.

TikTok's early entry into the short-video market also gave the company a big early-mover advantage. Meta's Instagram did not launch Reels until 2020, while Alphabet's YouTube launched Shorts in 2021, both of which lag TikTok in years of data and product development experience.

What does research reveal about the algorithm?

TikTok also regularly recommends content that falls outside of users' interests, which the company's management has repeatedly said is essential to TikTok's user experience.

A study, which researchers from the US and Germany published last year, found TikTok's algorithm "exploits user interests in 30% to 50% of the recommendation videos", after examining data from 347 TikTok users and five automated bots.

"This finding indicates that the TikTok algorithm opts to recommend a large number of explore videos in an attempt to either infer better the user interests or maximise user retention by recommending many videos that are outside of the user's (known) interests," the researchers wrote in the paper titled "TikTok and the Art of Personalization".