Facebook announced a tweak to its News Feed today that aims to reduce unwanted “spammy” content in user feeds. Good news for readers frustrated by those stories, bad news for the publishers that have been making money by promoting their websites via “clickbait.” But what exactly is clickbait?

@greghoward88 lol clickbait now just means "things I don't personally like"

— Charlie Warzel (@cwarzel) August 21, 2014

Clickbait is in the eye of the beholder, but Facebook defines it as “when a publisher posts a link with a headline that encourages people to click to see more, without telling them much information about what they will see.” But they won’t be demoting links based on verbal clues.

So how do we determine what looks like click-bait?

One way is to look at how long people spend reading an article away from Facebook. If people click on an article and spend time reading it, it suggests they clicked through to something valuable. If they click through to a link and then come straight back to Facebook, it suggests that they didn’t find something that they wanted. With this update we will start taking into account whether people tend to spend time away from Facebook after clicking a link, or whether they tend to come straight back to News Feed when we rank stories with links in them.

Another factor we will use to try and show fewer of these types of stories is to look at the ratio of people clicking on the content compared to people discussing and sharing it with their friends. If a lot of people click on the link, but relatively few people click Like, or comment on the story when they return to Facebook, this also suggests that people didn’t click through to something that was valuable to them.

In other words, if people aren’t reading or talking about your content, soon they might not see it on Facebook at all.

Lots of people assume that sites that pull in huge traffic from social media — like BuzzFeed, for example — achieve those figures by using “clickbait.” But in reality, original content, even in list format, is something people are likely to read and share and comment on, which means Facebook is probably fine with it. Even lower brow sites that try to churn out viral headlines might evade this new News Feed obstacle if they can get people to spend a few minutes on site. As The Awl’s John Herrman points out on Twitter, that doesn’t jive with how people in the media define clickbait.

@kevinroose I think time-on-site favors a lot of stuff that media people equate with "clickbait"

— John Herrman (@jwherrman) August 25, 2014

Facebook doesn’t have any editorial obligation to promote breaking news or think pieces or longform; their obligation, as they’ve repeatedly stated, is to satisfy their users. Apparently, the company feels the best way to determine if users are satisfied is by measuring the length of time they spend looking at something.

Facebook is a platform with enormous power over publishers. If they’re making moves toward time on site as a lead metric, you can bet content strategists across the web are already coming up with ways to hang on to your eyeballs.