About half of Facebook users are uncomfortable with how the social media site targets them for ads while a smaller number don’t like how their political leanings are described, new research says.

The survey of a nationally representative sample of 963 Facebook users found that 88 percent, a large majority, have their traits and interests categorized, according to the results of a study released this week by the Pew Research Center.

But 74 percent of Facebook users, said they did not know this list of categories existed until being directed to the page during the survey, Pew said. “Moreover, once shown how the platform classifies their behaviors and personas, roughly half of Facebook users, or 51 percent, say they are not comfortable that the company created such a list,” the study said.

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The study underscores the growing distrust of Facebook against a backdrop of how the company leverages users – often unbeknownst to them – to make money, according to one analyst.

“The tricky thing about trust is once it’s gone, it’s very, very hard to regain it. That’s the Facebook situation right now,” Karsten Weide, an analyst at Framingham, MA.-based IDC, told Fox News. “They [Facebook] have to be transparent and give users better opportunity to turn things on and off in terms of how they’re being tracked,” he added.

The other side of the argument is, “if you get stuff for free, you’re going to get advertising,” he said.

Facebook says it’s trying to be more proactive in educating users. “We want people to understand how our ad settings and controls work,” a Facebook spokesperson told Fox News.

“While we and the rest of the online ad industry need to do more to educate people on how interest-based advertising works and how we protect people’s information, we welcome conversations about transparency and control,” the spokesperson added.

How did this happen?

Facebook analyzes “scores of different dimensions of its users’ lives” then invites advertisers to target them, Pew said.

A partial list of how Facebook classifies users can be found on “Your ad preferences” page. The page lists, among other things, interests based on Facebook’s algorithm, which, in turn, is based on data provided by users and content they have “posted, liked, commented on and shared,” Pew Research said.

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And there are other advertising tools unknown to users such as Facebook pixel, which records the activity of users on advertisers’ websites and passes this data back to Facebook.

"Millions of companies and organizations around the world have activated the Facebook pixel on their websites," Pew said.

Political labels

On another front, political labels are commonly assigned to Facebook users, Pew said. About half of those in the Pew survey were given such a label.

While 73 percent said the listing very accurately or somewhat accurately describes their views, 27 percent said those that the label is not very or not at all accurate, according to Pew.