Since the Cambridge Analytica scandal broke, one question has been on everyone’s minds:

So what happened, exactly?

This timeline is Quartz’s attempt to offer a comprehensive, yet clear, explanation of how Cambridge Analytica came to use the data of 50 million Facebook users, collected without their permission, to target potential Trump voters during the 2016 US presidential election. We’re also tracking the ongoing fallout from the scandal, which has engulfed Facebook and its CEO Mark Zuckerberg in an unprecedented backlash.

We’ll continue updating the timeline as more information comes out. For more information about a given event, just click on the bubble at the end of each sentence.

2010

Facebook launches the first version of Open Graph API, which allows outside app developers to access

1 Quizzes and personality tests were all that anyone posted on Facebook around 2010. Everything about you, from your hometown to whether you like the band Metallica, is at the time accessible to the people who develop these quirky tests , who are not employed by Facebook. They can also access the data of friends of people who had taken the test or used the app, and link up all the information they have on a user from multiple apps.

2011

The US Federal Trade Commission and Facebook sign a consent decree in which the company promises it won’t share users’ data .

2 The FTC says Facebook engaged in deceptive practices by making public data users thought was private, and that it shouldn’t have shared data with outside actors like advertisers or app developers.

2013

UK-based Strategic Communication Laboratories Group (SCL) founds Cambridge Analytica as its US arm for operations. The move is orchestrated by alt-right publisher

3 The 25-year-old SCL Group had previously worked with corporate and government clients to deliver insight into the minds of customers and enemies of governments. Money for the new venture comes in part from the Mercer family, a Republican mega-donor and Breitbart News backer.

2014

Cambridge Analytica gets data on Facebook users from Cambridge University researcher Aleksandr Kogan, in violation of



4 After Cambridge University’s Psychometric Centre, which had been gathering personality data through a Facebook quiz for scientific purposes since 2007, refuses to work with the data firm, researcher Aleksandr Kogan creates a similar app. Cambridge Analytica pays Kogan to set up a personality quiz, and he recruits 270,000 people through Amazon’s Mechanical Turk freelance job boards to take it, paying them $1-$2. They agree for their data to be collected “for academic purposes,” but the app also accesses the information of their friends—who did not give any sort of consent for their information to be shared. This brings up the total number of user profiles Cambridge Analytica has in its trove to more than 50 million. Kogan, who is operating as part of his own company, Global Science Research, assures the test-takers that their data will be anonymous and safe, but some raise security concerns. In 2018, Kogan claims he did not know what specifically Cambridge Analytica wanted to use the data for other than political consulting work.

Cambridge Analytica works on the 2014

5 The company providing conservative candidates with communications, polling, and research services, including a super PAC—an organization that raises money for political candidates—formed to support John Bolton , the hawkish former UN ambassador (hired by Trump in 2018 as the national security advisor). The New York Times reported in 2018 that the super PAC hired Cambridge Analytica specifically to develop psychological profiles derived from Facebook data.

Christopher Wylie, a data scientist who helped build Cambridge Analytica and would go on to be the key whistleblower in the scandal, leaves the company in July.

Facebook starts to change its policies on using

6 First, in April , it starts to phase out the existing version of Open Graph API, limiting permissions for third-party applications (although not retroactively) and in October, after a study on emotional manipulation blows up into a PR disaster, it establishes a review process for researchers who want to use Facebook data.

2015

Wylie, who started his own company after leaving Cambridge Analytica, still has the harvested Facebook data in his possession—but he says he deletes it

7 Wylie recently testified before UK lawmakers that he didn’t use the Facebook data in his work. “I didn’t do any contracts or do any, you know, work with that data,” he said. “I haven’t worked with any clients… That data got deleted, I believe, in 2015 on my end.”

March-April

Wylie’s company, Eunoia Technologies, meets with Donald Trump’s campaign operative Corey Lewandowski to discuss

8 While it’s not clear that Wylie’s company proposed using the Facebook data to target voters on behalf of Trump, the meeting suggests some level of hypocrisy in Wylie’s ethical concerns that Cambridge Analytica had taken meetings with the Trump campaign. BuzzFeed News, which broke the story, also notes that the mere fact that Wylie was in possession of the harvested Facebook data offers "further evidence that the company is unable to track how the personal profile information it collects is employed and distributed by third parties."

November

Bloomberg reports that the pro-Brexit campaign group Leave.EU, headed by Nigel Farage, has hired

9 A Cambridge employee tells Bloomberg that the company plans to interview “close to half a million Britons” in order to build profiles of swing voters.

December

A report in The Guardian shows that Republican presidential nominee Ted Cruz had hired

10 A report from The Guardian reveals that Cambridge Analytica was using its vast number of harvested Facebook profiles to target US voters. Facebook tells The Guardian it will take "swift action." Facebook says it removed Kogan’s personality quiz app in 2015, and that this was also the point when it “required certification” from everyone who had copies of the data that they had destroyed it. Cambridge Analytica claims it did what Facebook asked in 2015. Wylie only received a letter from Facebook asking him to delete the data in the latter half of 2016, according to the Guardian, and news reports suggest the harvested data is still circulating today.

2016

After the Cruz campaign folds, Cambridge Analytica is hired by Donald Trump’s

11 There’s some debate on how much influence Cambridge Analytica had on the Trump campaign. We know that the company worked out of the offices of the Trump campaign’s digital operation in San Antonio. Company representatives were caught on tape boasting about how Cambridge Analytica was instrumental to Trump’s win. A leaked campaign debrief that the company prepared for Trump says that Cambridge Analytica targeted Americans with 10,000 different ads over the internet, which were viewed billions of times.

AggregateIQ, a Canadian firm employed by SCL Group that was reportedly referred to internally as a branch of Cambridge Analytica, is hired by the other major pro-Brexit group,

Both Trump and the “Leave” faction win their respective votes.

2017

Special counsel Robert Mueller requests files from Cambridge Analytica in relation to Russian interference in US presidential election,

13 Mueller requested any internal emails from the firm. Cambridge Analytica CEO Alexander Nix had reportedly contacted WikiLeaks founder Julian Assange to obtain harmful emails about the Clinton campaign around the time Cambridge Analytica joined the Trump campaign.

2018

March

Blockbuster reports from The New York Times and The Observer show that the scale of the data harvesting by Kogan and Cambridge Analytica was much bigger

14 Wylie discloses details of the operation to reporters, who also see the raw data that Cambridge Analytica supposedly deleted. Trying to get out in front of the news, Facebook announces it is investigating the matter and suspends Cambridge Analytica from Facebook. But very few believe in the company’s good intentions, and the company receives enormous backlash over how it handled the situation. The revelations also resurface questions about Facebook’s business model, which ultimately is what allowed the data to leak out.

Cambridge Analytica is in a lot of trouble. Its executives are caught on tape boasting about using shady and illegal practices in their work

15 The UK TV station Channel 4 broadcasts its investigation on Cambridge Analytica, in which an undercover reporter meets with the company’s representatives. They brag about using different techniques of political intimidation, including hiring Ukrainian sex workers, and blackmail. In the tapes, an executives says the company staged the Kenyan election . The company’s CEO, Alexander Nix, says Cambridge Analytica ran the entire Trump campaign . Nix is also suspended by the company’s board.

After days of silence, Mark Zuckerberg finally

16 Zuckerberg initially gives a non-apology, saying the company already fixed most of the problems. He later adds that he is sorry about what happened. He tells CNN that he isn’t opposed to regulating Facebook . He announces several changes that the company is planning to make, including restricting developers’ access to data.

Lawmakers demand Facebook explain itself, while regulators and other officials launch investigations into its actions. The company also faces a boycott from users, and

17 The company faces hearings and probes in several countries. Zuckerberg is summoned by US congressional committees to testify—and he reportedly decides that he will do so. The Federal Trade Commission says it is investigating whether the company had violated the 2011 consent decree; the company could face hefty fines as a result. Users declare en masse that they will delete Facebook, although this is much harder than it seems . The company’s business takes a hit, losing about $100 billion in market value. Some advertisers say they are pulling out of the platform.

Michael Coren contributed to this story.