Consultants working for Donald Trump’s presidential campaign exploited the personal Facebook data of millions.

That’s the key message in Saturday stories by The New York Times and the UK’s Guardian and Observer newspapers, as well as in statements from Facebook. The stories and statements indicate the social networking giant was duped by researchers, who reportedly gained access to the data of more than 50 million Facebook users, which was then misused for political ads during the 2016 US presidential election.

Until now, most of what you’ve heard about Facebook and the 2016 election has been focused on meddling by Russian operatives. Those efforts are being investigated by the FBI and the US Senate. 

Data consultancy Cambridge Analytica represents a different problem. In its case, the UK-based company reportedly acquired data about millions of Facebook users in a way that violated the social network’s policies. It then tapped that information to build psychographic profiles of users and their friends, which were utilized for targeted political ads in the UK’s Brexit campaign, as well as by Trump’s team during the 2016 US election. 

Facebook says it told Cambridge Analytica to delete the data but that reports suggest the info wasn’t destroyed. Cambridge Analytica says it complies with the social network’s rules, only receives data “obtained legally and fairly,” and that it did indeed wipe out the data Facebook is worried about.

Here’s what you need to know.

What is Cambridge Analytica?

Cambridge Analytica is a UK-based data analytics firm that helps political campaigns reach potential voters online. The company combines data from multiple sources, including online information and polling, to build “profiles” of voters. The company then uses computer programs to predict voter behavior, which then can potentially be influenced through specialized advertisements aimed at the voters.

Cambridge Analytica isn’t working with a small amount of data either. The company claims to have “5,000 data points on over 230 million American voters” — or pretty much all of us, considering there are an estimated 250 million people of voting age in the US. 

What did Cambridge Analytica do?

Facebook said in a statement published late Friday that Cambridge Analytica received data from Aleksandr Kogan, a lecturer at the University of Cambridge. Kogan allegedly created an app called “thisisyourdigitallife,” which ostensibly offered personality predictions to users and while calling itself a research tool for psychologists.

The app asked users to log in using their Facebook account. As part of the login process, it asked for access to users’ Facebook profiles, location, what they liked on the service, and importantly, their friends’ data as well.

The problem, Facebook says, is that Kogan then sent this data to Cambridge Analytica without user permission, something that’s against the social network’s rules.

“Although Kogan gained access to this information in a legitimate way and through the proper channels that governed all developers on Facebook at that time, he did not subsequently abide by our rules,” Paul Grewal, a VP and general counsel at Facebook, said in a statement.

Kogan didn’t respond to requests for comment. The New York Times said he cited nondisclosure agreements and declined to provide details about what happened, saying his program was “a very standard vanilla Facebook app.”

What does this have to do with Trump?

Trump’s campaign hired Cambridge Analytica to run data operations during the 2016 election. The company helped the campaign identify voters to target with ads, and gave advice on how best to focus its approach, such as where to make campaign stops and what to say in speeches.

“The applications of what we do are endless,” Cambridge Analytica CEO Alexander Nix said last year in an interview with CNET sister site TechRepublic.

The White House didn’t respond to a request for comment.

Cambridge Analytica also worked with other 2016 presidential campaigns, according to its website and various media reports. Those included the campaigns of Sen. Ted Cruz and of Ben Carson, who went on to join Trump’s cabinet as secretary of housing and urban development. 

Why did Facebook ban Cambridge Analytica from its service? 

Facebook said Cambridge Analytica “certified” three years ago that it had deleted the information, as did Kogan. But since then, Facebook said, it’s received reports that not all the data was deleted. The New York Times reported in an article Saturday that at least some of the data remains.

Cambridge Analytica said in a statement Saturday that it deleted all the data and is in contact with Facebook about the issue.

Was Facebook hacked?

The New York Times characterizes this as a “breach” and says it’s “one of the largest data leaks in the social network’s history.” That’s in part because the roughly 270,000 users who gave Kogan access to their information allowed him to collect data on their friends as well. In total, more than 50 million Facebook users are said to have been affected.

The misuse of this data is what The New York Times zeroed in on.

Facebook, however, says that though Kogan mishandled its data, all the information Kogan got was accessed legally, and within its rules. The problem is that Kogan was supposed to hold onto the information himself, not hand it over to Cambridge Analytica or anyone else.

Still, Facebook says that it wasn’t a “breach” because the information was accessed through normal means — using an app that asked people for access to their information, which they then agreed to.

Facebook argued its point even further in an update to its Friday statement, saying that calling this episode a “breach” is “false.”

“People knowingly provided their information, no systems were infiltrated, and no passwords or sensitive pieces of information were stolen or hacked,” the company said.

Of course, critics point out that Kogan was able to do what he allegedly did because Facebook allowed app developers to request and receive access to a person’s friend’s data. Facebook changed that policy in 2015, prohibiting the practice.

Wait, so Facebook allows apps to access my data?

When you log in to an app using your Facebook account, the developer typically asks for access to information the social network has. Sometimes it’s just your name and email. Other times, it’s your location and friends’ data too.

All this is pretty much what any app developer that works with Facebook is allowed to do. That is, until 2015 when Facebook stopped app developers from having access to friends’ data. The rest, though, is still fair game.

Facebook says its rules specify that developers can’t share the information they receive with other companies. That’s where the problem with Kogan and Cambridge Analytica comes up.

But everything else? That’s fine by Facebook. The company has an app review process it puts developers through, but once they’re cleared, things are A-OK.

You hand your information over to app developers all the time. Don’t like it? Think before you click, and read the requests from app developers more carefully.

What can I do?

There isn’t much. You may’ve been swept up in this without even knowing it. You don’t have to have downloaded Kogan’s app to have had your information accessed, since the statements and articles say the app slurped up information about users’ friends.

Cambridge Analytica also doesn’t appear to offer a way for you to request your information be removed from its systems. The company didn’t respond to a request for comment.

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