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Gold1400

System Design

Feed Ranking Signals

The inputs a feed uses to decide which posts rise above pure recency.

4 min read · core · beat Gold to climb

Beyond newest first

A reverse chronological feed is simple but often shows low value posts just because they are recent. A ranked feed scores each candidate post and orders by score, so the most engaging content rises.

Ranking takes a set of signals as input and combines them into one number per post.

Common signals

  • Recency. How fresh the post is. Older posts decay.
  • Affinity. How close the viewer is to the author, based on past interaction.
  • Engagement. Likes, comments, and shares the post is gathering.
  • Content type. Whether the viewer tends to engage with video, photos, or text.
  • Negative signals. Hides, reports, and quick scroll past lower a post.

How signals combine

Early systems used a fixed weighted formula. Modern systems feed the signals into a machine learning model that predicts the chance the viewer will engage, then ranks by that predicted value.

The output is a ranked candidate list, which later stages may further filter for diversity and policy.

Key idea

A ranked feed scores candidates from signals like recency, affinity, and engagement, often via a model that predicts viewer interaction, instead of pure recency.

Check yourself

Answer to earn rating on the learn ladder.

1. Why do systems rank rather than sort by time alone?

2. Which is a negative ranking signal?

3. How do modern feeds combine signals?