How Facebook decides what you see in your News Feed

(Update: I’ve added some new material at the bottom of this post.)

With nearly a billion users and hundreds of thousands of advertisers, Facebook says it has more content than it can possibly show to each person who signs on to the social network.

That means users will never see everything that’s posted by every friend or company whose page a user has liked.  At a press event Friday, the company pulled back the curtain a bit, while discussing the algorithms that determine which items actually show up in each user’s news feed.

And if you’re a “lurker,” take note:  The algorithms rely heavily on “interaction” — ie, how often a user comments or “likes” or shares things — to determine whether a post is something a user wants to see, according to Will Cathcart, a Facebook product manager.

While the company considers a number of variables, Cathcart said these are the main  factors that determine which items to include in a user’s news feed:

• How has the user interacted with posts from that source before?  In other words, has the user liked or shared posts from the source, or has she ignored it?
• How have other users reacted to this particular post? Are a lot of other people sharing it or commenting on it?
• How has the user reacted to other posts of a similar  type in the past? Is the user more likely to react to stories about a friend’s relationship with other friends, messages from commercial pages, or updates from games or other apps?
• Since September, Facebook has also begun factoring in the likelihood that a user will complain or mark a post as spam.

Facebook, of course, will also let users and advertisers pay for “promoted posts,” which may be shown to more friends  - or people who liked a company’s page – than would ordinarily see it. So you might see a promoted post even if you rarely interact with that source.

But another product director, Matt Idema, said Facebook’s goal is to deliver material, including ads, that its members find interesting or useful.  So promoted posts are also delivered according to algorithms that take into account the volume of past interactions as well as demographic and even geographic factors, such as physical proximity to the business that is sending a promoted post.

Facebook also uses other criteria to determine what to show on mobile devices as opposed to the web version of the service. For example, mobile users are less likely to view a video on their smartphone, so they may not be shown as many video links, Cathcart said.

Some well-known Facebook users, including Star Trek actor George Takei and sports magnate Mark Cuban, have complained in recent weeks that Facebook is showing fewer updates from their pages, suggesting the company is trying to sell more paid posts. Facebook denies this, while saying it’s constantly adjusting its algorithms to deliver the most relevant results.

Facebook also has specialized feeds, including a Pages Feed and a Games Feed, where users can find more of certain types of posts. But the company says it no longer offers a complete feed of every message posted by all your friends and companies you’ve liked.

“The problem we have is that users come to Facebook every day and we have lots of stuff happening on Facebook, but people don’t generally have enough time to check out everything that’s happening,” Cathcart said.

Brandon Bailey (142 Posts)

Brandon Bailey covers Google, Facebook and Yahoo for the San Jose Mercury News, reporting on the business and culture of the Internet.