Facebook is rolling out changes to its News Feed designed to show you older stories you haven't read yet, as long as the company's algorithms believe those stories will be interesting to you, the company said today. At an event at the company's Menlo Park campus, executives unveiled "story bumping." The feature shows off older stories that you didn't read but are popular in your feed, as determined by the number of shares, likes, comments, and clicks they receive.

It's designed to solve a problem often experienced by the 700 million-plus daily visitors to the News Feed: missing stories that are important to them, whether that be a photo of a beloved nephew or an updated relationship status for a person they care about. A large part of the problem is volume: the average Facebook user has 1,500 potential stories flowing through their feed each day.

The average Facebook user has 1,500 potential stories flowing through their feed each day

The feature originated during regular chats with Facebook's News Feed team, said Lars Backstrom, engineering manager for news feed ranking. Chris Cox, Facebook's vice president for product, noticed that a photo his friend had taken seemingly hadn't shown up in his feed. The company investigated and found that the photo had gone into the feed, but Cox never scrolled down far enough to see it.

That led to discussions about how to let users see stories that they were likely to care about but that they never got around to reading. The company tested a method of discovery that involves bumping up unseen older stories on top of newer ones. To do it, the company had to build new methods to determine what stories on News Feed users had actually seen. Three engineers took months to put the new system together, Backstrom said.

"People are able to read a larger fraction of their stories."

Early tests have shown that users like the feature, Backstrom said. Users were 5 percent more likely to engage with a friend's post, 8 percent more likely to engage with a brand or publisher's post, and wound up reading 13 percent more of the available stories in the feed. "It sort of had the desired effect," Backstrom said. "People are able to read a larger fraction of their stories."

The latest tweaks to the News Feed, a product that turns 7 years old next month, come a few months after Facebook separated different types of content into different feeds. In March, the company moved to a "personalized newspaper" philosophy for the News Feed, making it easier to browse photos, music, and stories from close friends, among other categories. Previously, Facebook bumped weddings and engagements to the top of the feed; before that, the company altered the feed to show more photos.

Story bumping has launched on the web and is still rolling out on mobile devices, the company said.