By Justin Osofsky, VP Global Operations

At Facebook, we stand for connecting every person — for a global community, for bringing people together, for giving all people a voice, for a free flow of ideas and culture across nations.

One of the most powerful ways people connect is around major events — in their communities and in the larger world. People also connect through conversations on the topics they are most interested in.

At its core, Trending Topics is designed to help people discover major events and meaningful conversations. Trending Topics is a feature we added in 2014 — separate from a person’s News Feed — to help people discover content that is both popular in the world and meaningful to them. Topics that are eligible to appear in the product are surfaced by our algorithms, not people. This product also has a team of people who play an important role in making sure that what appears in Trending Topics is high-quality and useful.

The Trending Topics team is governed by a set of guidelines meant to ensure a high-quality product, consistent with Facebook’s deep commitment to being a platform for people of all viewpoints. Our goal has always been to deliver a valuable experience for the people who use our service. The guidelines demonstrate that we have a series of checks and balances in place to help surface the most important popular stories, regardless of where they fall on the ideological spectrum. Facebook does not allow or advise our reviewers to discriminate against sources of any political origin, period. Here are the guidelines we use.

Here is an overview of how Trending Topics works:

Surfaced by algorithm
Potential Trending Topics are first surfaced by an algorithm that identifies topics that have recently spiked in popularity on Facebook (in other words, ones that have a high volume of mentions and a sharp increase in mentions over a short period of time). The Trending Topics algorithm also uses an external RSS website crawler to identify breaking events so that we can connect people to conversations on Facebook about newsworthy events as quickly as possible. A list of included websites is available here.

Reviewed by the Trending Topics team
Members of the Trending team look at potential Trending Topics as they are surfaced by the algorithm and do the following:

Confirm that the topic is tied to a current news event in the real world (for example, the topic “#lunch” is talked about during lunch every day around the world, but will not be a trending topic). Write a topic description with information that is corroborated by reporting from at least three of a list of more than a thousand media outlets. A list of these media outlets is available here. Apply a category label to the topic (e.g. sports, science) to help with personalized ranking and to enable suggestions grouped by category for the various tabs on the desktop version. Check to see whether the topic is national or global breaking news that is being covered by most or all of ten major media outlets— and if it is, the topic is given an importance level that may make the topic more likely to be seen. A list of these outlets is available in the guidelines.

Personalized
The list of Trending Topics is then personalized for each user via an algorithm that relies on a number of factors, including the importance of the topic, Pages a person has liked, location (e.g.. home state sports news), feedback provided by the user about previous Trending Topics and what’s trending across Facebook overall. Not everyone sees the same topics at the same time.

The Trending search results page

When you click on a Trending Topic, you are taken to a search results page that includes all the news sources and posts that are covering the topic. The articles and posts that appear here are also surfaced algorithmically.

Trending is also integrated into Facebook Search so you can search for any Trending topic that may not show up in your Trending suggestions.

Q. Why was Trending Topics created?

Trending Topics was launched in 2014 to surface the major conversations happening on Facebook. It has evolved over time, and remains a work in progress. Trending Topics is a relatively limited part of the Facebook experience — appearing on the right hand side on desktop as well as when you tap on the Search box in the mobile app, and primarily for people using Facebook in English (there are limited tests being run in Spanish and Portuguese).

Q: How do you protect against bias in the Trending Topics product?

First and foremost, the algorithm that surfaces topics eligible for review optimizes for popularity and frequency on Facebook and whether it is a real world event — and does not consider perspective or politics. Second, we have a series of checks and balances in place to help surface the most important popular stories, regardless of where they fall on the ideological spectrum, as well as to eliminate noise that does not relate to a current newsworthy event but might otherwise be surfaced through our algorithm. Facebook does not allow or advise our reviewers to discriminate against sources of any political origin, period.

The guidelines that govern our review:

do not permit the suppression of political perspectives do not permit the prioritization of one ideological viewpoint over another

Lastly, we regularly audit the work of members of our review team to ensure that it complies with the guidelines. Violating the guidelines is a fireable offense.

Q. Have reviewers been instructed by Facebook to inject specific stories into Trending Topics to suppress conservative news/sites? 

No — and the guidelines do not permit reviewers to add or suppress political perspectives.

Q. What does ‘injecting’ mean? Could someone who is reviewing the Trending Topics artificially inject a topic into Trending Topics?

Potential Trending Topics are first surfaced by an algorithm that identifies topics that have recently spiked in popularity on Facebook or are suggested by an external RSS website crawler to identify breaking news events. If, in this process, a topic is detected that should connect to a linguistically-similar but distinct topic (e.g., the LEGO movie vs LEGO the toy), the reviewer may replace the topic ID by “injecting” a more accurate topic ID. Similarly, we might inject “#Odile” as a better way to represent a hurricane occurring in Cabo San Lucas than the topics “Baja” and “Cabo,” which might be surfaced by the algorithm. Injection helps improve Trending Topics over time by surfacing higher-quality topics. It is not used to promote articles or topics from a particular perspective.

Q: Can reviewers remove or suppress political topics they don’t like by “blacklisting” them? 

The guidelines do not permit the suppression of political perspectives. About 40% of the topics in the queue get rejected by the reviewers because they reflect what is considered “noise” — a random word or name that lots of people are using in lots of different ways. For example, braised, DVD, #weekend and #sale are all topics that were not accepted as trends over the past week. This tool is not used to suppress or remove articles or topics from a particular perspective.

Q. Is Facebook investigating whether employees did manipulate the Trending Topics list in ways alleged in the Gizmodo stories?

Yes. We take these reports very seriously, and will continue to investigate the allegations. We have found no evidence to date that Trending Topics was successfully manipulated, but will continue the review of all our practices.