Getty Images / Tobias Schwarz

Facebook's trending stories, which were introduced to the website in 2014, have come under fire this week after a Gizmodo report claimed former 'news curators' at the company had manipulated results.

After The Guardian published leaked internal documents showing that human editors are heavily involved in the selection of the stories that are displayed to millions of users, the company published its own, updated, version of the documents.


Human intervention in the process has proved controversial as many had believed Trending Topics were dictated by algorithms. "The topics you see are based on a number of factors including engagement, timeliness, Pages you've liked and your location," an explanation of Trending Topics says.

Facebook has consistently denied that those working as part of its team select news based on political opinions. "Facebook does not allow or advise our reviewers to discriminate against sources of any political origin, period," the company said in a blogpost accompanying the publication of its editorial guidelines.

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CEO Mark Zuckerberg has also been drawn into the debate and said his staff were conducting a "full investigation" into how the Trending Topics are managed. "We have found no evidence that this report is true. If we find anything against our principles, you have my commitment that we will take additional steps to address it," he wrote on Facebook.

Those working on Trending Topics are split into three individual teams that curate and rank the content, according to official guidelines shared by Facebook.


The editorial team has responsibility for accepting the topics that are based on real-world events. "We provide context to help people understand the trend and metadata to inform the algorithms that target trends," the document reads.

The topics you see are based on a number of factors including engagement, timeliness, Pages you've liked and your location Facebook

A 'topic detection team' is then responsible for surfacing 'pending topics' that may become relevant in the near future and then providing them with a rank. A third team's job is to provide ranked feeds when the news topic has been accepted.

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Staff are told to assume that every topic is real, until it has been proven not to be. Stories are also ranked based on their significance.


One section of the document explains what happens when a major news story breaks, Facebook calls these moments the "'Holy S**t' stories," that may only happen a few times per year. It gives examples of terrorists killing staff at Charlie Hebdo.

A number of basic criteria are needed for topics to be included as exceptional stories, the documents from Facebook explain. To be considered, topics have to be covered by ten leading news websites, and be the "most prominent" on at least eight of them and have "hard news" behind them.

Write a custom topic name for breaking or planned news events that are expected to persist for several days Facebook

For the more regular stories, Facebook explains they should be one of the "top stories of the day". The websites it judges all stories against include, what it calls, the leading websites: BBC News, CNN, Fox News, The Guardian, NBC News, The New York Times, USA TODAY, The Wall Street Journal, Washington Post and BuzzFeed News.

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Once a story has been chosen by staff it is added to a category and, if available, better images are used.

Staff are also able to rewrite topics and give them "custom topic names" in some circumstances. Circumstances include trending topics with the wrong name, names that are too long or where the location isn't clear. "Write a custom topic name for breaking or planned news events that are expected to persist for several days," the document explains.


There are also guidelines for blacklisting content. Facebook says it blacklists items for two reasons: "junk topics" that don't represent real-world events and duplicate events.

Staff deciding to blacklist a topic pick a number of hours it can't be considered for inclusion in the list, this is usually for a 24 hour period, according to Facebook. When staff blacklist a topic they have to provide a reason for doing so and Facebook lists six separate areas that fall under "junk topics" and non-real world events. These include if the story is stale or has a low quality hashtag.

Stories with insufficient sources also shouldn't be included: "Use this when we think a topic is connected to a real-world event but the available information is not sufficient to characterise the topic with confidence," Facebook's guidelines explain. 'Hoax sources' should also not be added to Trending Topics.