When it comes to expressing political views, Facebook can be one of the most hostile platforms. Just when users think that their opinions have no consequence, however, it turns out that the social network was actually gathering data on them even as they went on their tirade. As a result, Facebook now knows the political views of its users and is using that information to sell ads to corporations.

As the New York Times discovered, even the smallest of details is enough for Facebook to categorize American users into the political affiliation that they have even when they didn’t indicate it as they created their profile. All they would need to do is visit facebook.com/ads/preferences, click the “Lifestyle and Culture” tab, which is under the header titled “Interests,” and find a box that is labeled “US Politics.”

Apparently, aside from posting their views on their accounts, Facebook can determine what political affiliation users have through the pages that they visit, the groups they belong to, and even the products that they liked. In terms of the latter, products apparently indicate political affiliation via the companies that make them.

These are valuable pieces of information for the social media site because they can then use it to sell ads to corporations or particular groups, which will then target particular demographics. The NYTimes used the campaign by Donald Trump as an example, citing how ads for the Republican presidential nominee is paying Facebook to show political ads to users who are categorized as moderates.

On the other hand, users can easily delete any data that the Ad Preference page has on them, as Mashable reports. More than that, users who have indicated what their political affiliation is have been targets of specific ads for years, so this new development is not considered nefarious by any means.

What does raise some concerns, however, is the matter of media bias. By giving news outlets access to the political affiliation of its users, Facebook might accidentally cause some users to miss out on information that would challenge their own ideas.