Facebook is tweaking its News Feed to help users spot popular posts that they might have missed.
The News Feed update comes just as the social network takes on critics frustrated by the company's ranking of friends' posts instead of showing them all in chronological order.
"Now, organic stories that people did not scroll down far enough to see can reappear near the top of News Feed if the stories are still getting lots of likes and comments," wrote Facebook engineer Lars Backstrom in a blog post. "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."
For Facebook page owners, that means a second chance at getting their posts in front of users' eyes.
Backstrom noted that until now, people on average read 57% of the stories in their News Feeds. Simply put, they don't scroll far enough down to see the other 43%.
When those unread stories resurfaced, the overall fraction of stories read increased to 70%, he added.
The change also makes users more engaged.
In a recent test with what Facebook described as a "small number of users," recycling posts resulted in a 5% increase in the number of likes, comments and shares on friends' posts and an 8% increase in posts on brand pages.
Backstrom, though, wasn't just dealing with today's update to Facebook's News Feed. He also took on the ongoing criticism that Facebook uses an algorithm to bring users the posts the social network calculates they want to see, rather than just showing them each post as it comes online.
"The goal of News Feed is to deliver the right content to the right people at the right time so they don't miss the stories that are important to them," he explained. "This is no small technical feat: every time someone visits News Feed there are on average 1,500 potential stories from friends, people they follow and Pages for them to see, and most people don't have enough time to see them all."
Facebook sorts through all the posts - everything from wedding photos posted by a best friend, to an acquaintance checking in to a restaurant.
"With so many stories, there is a good chance people would miss something they wanted to see if we displayed a continuous, unranked stream of information," added Backstrom. "Our ranking isn't perfect, but in our tests, when we stop ranking and instead show posts in chronological order, the number of stories people read and the likes and comments they make decrease."
So how does Facebook rank the posts?
The algorithm takes note of what posts and images users comment on and which ones they hide, how often a user interacts with a friend or brand and how many likes, shares and comments a post receives. Those are all factored into Facebook's decision-making process.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is email@example.com.