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Facebook Assigns ‘Ethnic Identities’ for More Than Just Movie Trailers

"Straight Outta Compton" New York Screening"Straight Outta Compton" New York Screening
Facebook had different "Straight Outta Compton" ads for different "ethnic affinity" groups.Photograph by Johnny Nunez — Getty Images

The news last week that Facebook screened different Straight Outta Compton trailers for black, white, and Hispanic viewers left some a little surprised:

But it turns out that the company has actually been working on this kind of targeted advertising for years. Facebook calls these ethnic groupings “multicultural affinity audiences.”

The company tells Ars Technica that Facebook doesn’t actually use these categories to determine your race.

Instead, by looking at things like user language, location, and interests, the social networking site assigns users an “ethnic affinity” from one of four broad groups: non-multicultural, African-American, Asian-American or U.S. Hispanic. Then the company uses the data to sell ads.

In other words, are you a better target for “African-American” advertisements on Facebook, or “Hispanic” ones? Or maybe the Straight Outta Compton commercial that’s more “non-multicultural”?

Facebook for business gives advertisers the option to target their ads toward these different “ethnic affinity” categories. In the Hispanic audience, for example, advertisers can further break down interest groups for ads based on a user’s language preference.

For more on Facebook and personalized ads, watch:

Facebook (FB) researchers have been studying ways to use data on diversity and user ethnicity or perceived ethnicity for years. In a 2010 study researchers at Facebook wrote, “The ethnicity of a user base is an important demographic indicator that can be used for marketing, compliance, and analytics.”

It’s part of the reason Facebook is such a powerful advertising force: The company is targeting not just racial preferences, but every possible facet of your personality to drive more personalized, compelling ads to your screen alongside your friends and photos.

The social networking site boasts its 29.2 million-member Hispanic “affinity” audience is on par with some of the big Hispanic TV networks. Of course, the difference between watching an ad on a channel like Telemundo or Univision and being served one on Facebook is that you never tuned in to the Hispanic affinity channel Facebook may have assigned you—the company picks it for you without your knowledge.

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Facebook’s three specific ethnic advertising categories collectively draw in about 54.3 million monthly Facebook users in the U.S., making them a relative drop in the bucket when it comes to the 1.59 billion logging in on Facebook around the world. Still, for individual users, being a part of one of these groups could change a lot about the ads you see when you log on to Facebook. Facebook did not immediately respond to Fortune’s request for comment about the company’s ethnic affinity audience groups.