Introduction to the TikTok recommendation system

How TikTok’s For You feed works

When you interact with content on TikTok, you provide us with a variety of signals. These signals assist our recommendation system in understanding the type of content you might enjoy. We use these signals to create a prediction score for different videos. This score is an estimate of how likely you are to interact with each of those videos. Videos with the highest score are selected to be served to your For You feed. Below is a snapshot of the factors that shape what you see in your feed.

Signals from you

The signals you provide when you engage with content on TikTok encompass a range of interactions, such as the videos you have viewed, liked, or shared. By interacting with content on TikTok, you inform the system about the content you might find relevant and useful, helping shape your unique For You feed experience.

See the appendix for examples of key signals utilized in the recommendation system.

Predictions

The recommendation system uses the signals you provide to predict which content you’re likely to enjoy. These predictions estimate the likelihood you will interact with a given video, for example, the probability of liking, sharing, commenting, or skipping a given video. By combining prediction scores for each of these interactions, we can arrive at an overall score for each video, with higher scores signifying a closer match to your preferences.

See the appendix for examples of the recommendation system’s key predictions.

Ranking

The ranking process sorts videos by their prediction scores, from high to low. Your For You feed is created from these top-ranked videos, provided they pass a final similarity check before being recommended.

Similarity check

Content similarity measures how different consecutive videos in your For You feed are. If some of the videos that the system has chosen as top-ranked for you are too similar to each other, we replace them with others to ensure a greater variety in the content you see. These efforts aim to reduce the chance of you viewing videos with repetitive themes and help you instead explore and discover different types of content.

Building for safety in the recommendation system

Community Guidelines

Our Community Guidelines set the rules that determine which types of content are not allowed on the platform. They also outline the categories of content that are not eligible for recommendation in the For You feed, which is an experience intended for a range of audiences, from teenagers to great grandparents. We deploy a mix of machine learning models and human reviews to enforce our Community Guidelines. If you come across a video you think goes against our rules, you can long-press on the video and select ‘Report’ from the pop-up menu to send send the video to our moderation team for review.

Youth safety

We prioritize safety so that we can provide teens on our platform with an age-appropriate TikTok experience. We recognize that while the vast breadth of content that is shared on TikTok adds to the rich diversity of the experience, not all of it may be suitable for younger audiences. We limit overtly mature content so it is not available anywhere on TikTok for accounts aged 13-17, and only viewable by adults 18 years and older. In addition, any content created by an account aged under 16 is not eligible for recommendation to the FYF.

Prioritizing safety when recommending content

While the recommendation system predicts what content you’re likely to enjoy, the moderation rules aim to ensure that this content adheres to our Community Guidelines. The result is a For You feed that reflects your individual interests while prioritizing safety.

• Our moderation system works to remove violative content and make content that is not suitable for a broad audience ineligible for recommendation. Only videos that pass moderation are included in the pool of videos that can be recommended to our community in the For You feed.
• Using the prediction scores, the recommendation system picks from the approved videos those we believe you are likely to enjoy.

How you can influence your For You feed

Aside from the signals you provide by how you interact with content on TikTok, there are additional tools we have built to help you better control what kind of content is recommended to you.

• Not interested: You can long-press on the video in your For You feed and select ‘Not interested’ from the pop-up menu. This will let us know you are not interested in this type of content and we will limit how much of that content we recommend in your feed.
• Video keyword filters: You can add keywords – both words or hashtags – you’d like to filter from your For You feed.
• For You refresh: To help you discover new content, you can refresh your For You feed, enabling you to explore entirely new sides of TikTok.

Appendix

This non-exhaustive list offers insight about the variety of signals and interactions the system utilizes to deliver personalized content to your FYF. The signals that serve as input to our system are dynamic and constantly updated to encourage evolving interests and a thriving ecosystem. If you are interested in learning more, head to our Help Center to view up-to-date information on how TikTok recommends content.

TikTok personalizes your For You feed based on various factors, including:

• Your region, aligning recommendations to local standards and cultural norms.
• The language your device is set to.
• Your device’s operating system.
• Videos you’ve recently interacted with, including those you watched, finished, liked, or skipped.
• Your follow relationships with other people on TikTok.

The system predicts a variety of interactions, including your likelihood to:

• Like, share, comment on, or mark a video as ‘Not Interested.’
• Follow the video’s author or interact with their profile.
• Finish, skip, or favorite a video.
• Spend a certain amount of time viewing a video.
• Tap the video’s soundtrack.

In addition to signals you create by interacting with content, we also take into account various signals about the video, including:

• The time the video was posted.
• The region the video was posted from.
• The language setting of the video’s author.
• The video’s soundtrack.
• The length of the video.
• The hashtags associated with the video.