(CNN) -- Facebook wants to make sure you don't miss the most important updates, photos, humblebrags and baby announcements from your friends.
The company on Tuesday announced a tweak to its News Feed that will take a popular story -- one that's getting lots of comments and likes -- and put it back at the top of your feed to make sure you don't miss it.
On a typical day, the average Facebook user is only seeing 20% of the posts from friends and pages that he or she follows. Where are the rest? Filtered out by Facebook, using algorithms it has developed to determine the stories and posts the social network thinks you'll care about most.
Now Facebook has decided to shed some light on the mysterious decisions that go into ranking the stories in the news feed. People have grumbled in the past about not having a pure, kitchen-sink feed of all their friends' updates, so the company is explaining a little about how it does what it does.
To figure out what posts to show, Facebook looks at a person's most recent everyday actions such as liking, sharing or hiding posts, the amount of interaction they have with people or pages, and a post's popularity among their group of friends.
Facebook displayed updates differently in the past. The social media site was once a chronologically ordered feed of all the things posted by friends and pages. But then its number of users soared -- now more than 1 billion -- and over time, most users collected so many connections that their bloated feeds became unwieldy.
On an average day, Facebook says you have about 1,500 posts from friends and pages you follow. But only about 300 of those appear in your feed. Facebook thinks showing all 1,500 stories would be overwhelming, and that people would miss important posts in that flood of updates.
The company did some tests and found that people read, comment and like fewer posts when faced with the entire unfiltered stream. Even with the shorter, ranked news feeds, people only read an average of 57% of the posts.
With the new tweak, older posts can resurface and the amount of stories read jumps to 70%, Facebook said. It also resulted in a 5% increase in likes, comments and shares on the resurrected posts from friends, and 8% increase in the same activity for posts from pages, it said.
"The data suggests that this update does a better job of showing people the stories they want to see, even if they missed them the first time," Facebook said in a blog post.
Facebook previously tried to profit from this system. Last year it tried out a feature that let people pay to promote their own posts, ensuring that they appeared at the top of their friends' streams instead of getting buried. Earlier this year it expanded the feature to friends' posts.
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