The overall goal is to get people to spend more time on the news feed and interact with more items — which, not coincidentally, exposes people to more ads. According to the company, changing the feed to bump up important older posts that were missed increased likes, comments and shares by 5 percent to 8 percent among users in a test group. Since no one has time to scroll through that many Facebook posts, items in the feed are ranked to put the most recent and relevant posts near the top. How does the system define relevance?
Users can decide what posts are relevant to them by liking them and then can hide the things they dislike.
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