Facebook has been slammed for failing to protect the data of more than 50 million users. Their data was used to further conservative political projects, including Brexit and Donald Trump's presidential victory. From a former White House strategist to a Canadian whistle blower, here are the people involved in what some are describing as Facebook's largest data breach.

A 28-year-old Canadian data analytics expert first blew the whistle on the scandal to Britain’s Observer newspaper. Christopher Wylie claims he set up the project for Cambridge Analytica and helped forge ties with Donald Trump’s campaign. He revealed that millions of profiles were hijacked to influence the election. Cambridge Analytica says Wylie has been "misrepresenting himself and the company."

Cambridge Analytica CEO, Alexander Nix, was one of several senior executives filmed by an undercover reporter from Britain's Channel 4. Nix claimed credit for Donald Trump's 2016 electoral victory. He also said his political consultancy could feed untraceable messages on social media. Executives bragged that the firm could use misinformation, bribery and even prostitutes to help win elections.

A Moldovan-born Cambridge University researcher developed a personality app that harvested the personal data of 30 million Facebook users. Aleksandr Kogan said he passed the information to Cambridge Analytica, under assurances that what he was doing was legal. But now he says the research firm and Facebook are scapegoating him over the scandal.

Facebook CEO Mark Zuckerberg was criticized for waiting for four days to respond to the scandal. His social media network claims to be the victim of the whole saga, insisting it was unaware of how the data was being used. Still, Zuckerberg has been summoned by the British and European parliaments, while US consumer regulators have launched an investigation into the firm's use of personal data.

Trump's former strategist Steve Bannon helped develop the populist, anti-Washington message that helped the billionaire win the White House. A founding member of right-wing outlet Breitbart News, Bannon is a former board member of Cambridge Analytica and brought in wealthy businessman Robert Mercer as a financial backer. He left the White House last August and Trump has since cut him off.

Whether hate speech, propaganda or activism, governments across the globe have upped efforts to curb content deemed illegal from circulating on social networks. From drawn-out court cases to blanket bans, DW examines how some countries try to stop the circulation of illicit content while others attempt to regulate social media.

After a public debate in Germany, a new law on social media came into effect in October. The legislation imposes heavy fines on social media companies, such as Facebook, for failing to take down posts containing hate speech. Facebook and other social media companies have complained about the law, saying that harsh rules might lead to unnecessary censorship.

In 2014, the European Court of Justice ruled that European citizens had the right to request search engines, such as Google and Bing, remove "inaccurate, inadequate, irrelevant or excessive" search results linked to their name. Although Google has complied with the ruling, it has done so reluctantly, warning that it could make the internet as "free as the world's least free place."

In May 2017, Ukraine imposed sanctions on Russian social media platforms and web services. The blanket ban affected millions of Ukrainian citizens, many of whom were anxious about their data. The move prompted young Ukrainians to protest on the streets, calling for the government to reinstate access to platforms that included VKontakte (VK), Russia's largest social network.

In 2015, the European Court of Justice ruled that Safe Harbor, a 15-year-old pact between the US and EU that allowed the transfer of personal data without prior approval, was effectively invalid. Austrian law student Max Schrems launched the legal proceedings against Facebook in response to revelations made by former US National Security Agency (NSA) contractor, Edward Snowden.

In China, the use of social media is highly regulated by the government. Beijing has effectively blocked access to thousands of websites and platforms, including Facebook, Twitter, Instagram and Pinterest. Instead, China offers its citizens access to local social media platforms, such as Weibo and WeChat, which boast hundreds of millions of monthly users.

Many politicians and media outlets blame Russia's influence for Donald Trump's election victory in 2016. Moscow reportedly used Facebook, Twitter, Google, and Instagram to shape public opinion on key issues. In October 2017, Twitter suspended over 2,750 accounts due to alleged Russian propaganda. The platform also banned ads from RT (formerly Russia Today) and the Sputnik news agency.

With social media under pressure for allowing alleged Russian meddling, Facebook announced a new project to combat such efforts in November 2017. The upcoming page will give users a chance to check if they "liked" or followed an alleged propaganda account on Facebook or Instagram. Meanwhile, Facebook has come under fire for not protecting user data in the wake of the Cambridge Analytica scandal.