So how does Facebook’s Trending algorithm actually work? Very few, if any, people outside of 1 Hacker Way really know, but over at Quartz, reporters Dave Gershgorn and Mike Murphy have tried to piece it together.

Facebook last week said it was changing its Trending feature by eliminating the short sentences that described each story. Instead, Trending now just features broad topics surfaced by the algorithm. (On Thursday morning, Van Morrison — it’s his birthday — and Brown Eyed Girls — the South Korean band, not the Van Morrison song — were trending on my Facebook.)

Facebook recently laid off 26 contract editors and curators, with a team of engineers now overseeing the algorithm. And hours after the company made the switch, it had already run into trouble by promoting fake news stories and viral stories, such as a man engaging with a McChicken sandwich in a lewd fashion.

According to Facebook’s guidelines, the engineers overseeing Trending are “responsible for accepting all algorithmically detected topics that reflect real-world events.” Quartz noted that the document doesn’t specifically mention hate speech, only instructing the engineers to delete stories that are sexual in nature or that aren’t tied to real-world events.

Examining previous news reports and Facebook’s own patents, Quartz found that “mentions” are a critical component to the algorithm. In a July 5 patent awarded to the company, it defines mentions as specific terms or hashtags that are trending:

According to the patent, as the algorithm processes mentions and finds matching keywords, like NBA Finals or Super Bowl, it begins to sort them into a topic. Then the topic is given a Trending score based on geographic location of users posting about it, the timeframe during which those posts were made, and weighted number of mentions, according to the patent. The most important part of this score seems to be timing—the more mentions over a shorter time period, the higher the Trending score the topic gets. After the Trending score is assigned internally, and ostensibly approved by a reviewer, the Trending topics that are displayed are personalized for each user. Geographic location is a big factor, but the algorithm described in the patent also weighs “gender, race, national origin, religion, age, marital status, disability, sexual orientation, education level, and socioeconomic status,” as well as previous interactions with other content.

Of course, this is only a patent and doesn’t necessarily correspond to what Facebook is currently using. However, the description in the patent matches well with the information Facebook has publicly released.

This Facebook News story is mostly speculation. After the Gizmodo dustup, Facebook won't tell anyone anything. https://t.co/siqmGZdcKJ

— David Auerbach (@AuerbachKeller) August 31, 2016

Facebook also said that it assigns less value to users who post more frequently.

the diminishing returns of Facebook engagement https://t.co/YdbHJuent5 pic.twitter.com/YyJNhKNEvX

— Kira Bindrim (@KiraBind) August 31, 2016

Even though it’s just a patent, the information gives us a window into how Facebook is thinking about the algorithm and what the implications are for news outlets and news consumers. More than 40 percent of Americans get their news from Facebook, according to a Pew report earlier this year. (Mark Zuckerberg also said this week that Facebook is a technology company, not a media company.) While it’s unclear how many of them actually use Trending, which is difficult to find in Facebook’s mobile apps, it clearly still wields some power.

7/FB algorithms are patented discrimination machines. That’s how they work. This is fine.https://t.co/Hbbu1Dfn59 pic.twitter.com/BEM7cpZexQ

— David Carroll (@profcarroll) August 31, 2016

On Twitter, University of North Carolina professor Zeynep Tufekci said Facebook’s (and other social networks’) approaches to trending topics could have serious implications around the world.

New details on Facebook trending. No real oversight of the algorithm. A disaster if FB scales this globally. Don't. pic.twitter.com/XMB8GxxjYD

— Zeynep Tufekci (@zeynep) August 31, 2016

Here's the Quartz article: https://t.co/l6GBenU3aL and here's Facebook's own guidelines. https://t.co/Jb1HLwkN4A This is playing with fire.

— Zeynep Tufekci (@zeynep) August 31, 2016

"An algorithm surfaced it; that's fine" already failing in English. Can you imagine Burma—where ethnic cleansing is organized on Facebook?

— Zeynep Tufekci (@zeynep) August 31, 2016

If something happens in English we notice it. It's awful to have nonsense about Megyn Kelly "trend" but the stakes are much lower here.

— Zeynep Tufekci (@zeynep) August 31, 2016

This is not a Facebook only problem. See the trending on Turkish Twitter right now. One hashtag is an ethnic slur. pic.twitter.com/VnlrvSoHen

— Zeynep Tufekci (@zeynep) August 31, 2016

I worry about Twitter trending; I worry Google results but Facebook must triple worry. Bigger, more potential to organize collective action.

— Zeynep Tufekci (@zeynep) August 31, 2016

Trending teams must review topics to vet them—especially for vicious hate speech—especially outside the US where they don't notice.

— Zeynep Tufekci (@zeynep) August 31, 2016

"Little to no vetting" may feel like it'll save execs some headaches—but you'll instead end up in history books, as part of horrible events.

— Zeynep Tufekci (@zeynep) August 31, 2016