Mark Zuckerberg, Facebook's founder, has admitted that millions of Facebook users have had their data exploited by a political consultancy, Cambridge Analytica, after the social network "made mistakes".
The consultancy has been accused of improperly using the data on behalf of political clients.
In a statement posted on Facebook, Mr Zuckerberg said a "breach of trust" had occurred and, because of this, has promised to make it far more difficult for apps to "harvest" user information.
"We have a responsibility to protect your data, and if we can't then we don't deserve to serve you," Mr Zuckerberg said.
Talking with CNN, he said he was "really sorry", and pledged to take action against "rogue apps" while adding that he was "happy" to testify before Congress "if it's the right thing to do".
With the pressure on Facebook mounting, Mr Zukerberg said they'll address current and past problems by:
investigating all Facebook apps that had access to large amounts of information before the platform was changed "to dramatically reduce data access" in 2014
conduct a "full forensic audit" of any app with suspicious activity
ban any developer that did not agree to a thorough audit
ban developers that had misused personally identifiable information, and "tell everyone affected by those apps"
He added that, in future, Facebook would:
restrict developers' data access "even further" to prevent other kinds of abuse
remove developers' access to a user's data if the user hadn't activated the developer's app for three months
reduce the data that users give an app when they sign in to just name, profile photo, and email address
require developers to obtain approval and also sign a contract in order to ask anyone for access to their posts or other private data
"While this specific issue involving Cambridge Analytica should no longer happen with new apps today, that doesn't change what happened in the past.
"We will learn from this experience to secure our platform further and make our community safer for everyone going forward," Mr Zuckerberg said.
To put this all in perspective, in 2014, around 270,000 users responded to the invitation from Facebook to determine their personality type via a quiz called This is Your Digital Life, developed by Dr Aleksandr Kogan, a Cambridge University researcher.
Not only did the quiz collect data from the users who responded but
also some public data from those users' friends too.
A whistleblower, Christopher Wylie, says that data of more than 50 million people were harvested for Cambridge Analytica before Facebook restricted the amount of data developers can gather in this way.
Mr Wylie claims the data was sold to Cambridge Analytica who used it to "psychologically profile" people so they could deliver pro-Trump campaign material to them.
Alexander Nix, chief executive of Cambridge Analytica was suspended on Tuesday. This follows a story of a Channel 4 investigation where he was secretly recorded as saying the London-based company ran Donald Trump's digital campaign during the 2016 US election.
"We did all the research, all the data, all the analytics, all the targeting, we ran all the digital campaign, the television campaign and our data-informed all the strategy," he added.
Cambridge Analytica claims everything they had done was legal, and that Dr Kogan was being made a "scapegoat".
Facebook refutes the claim by Cambridge Analytica that they deleted the legitimately obtained user data when told to so by Facebook.
The firm said the report of comments secretly recorded by Channel 4 News had "grossly misrepresented" Mr Nix's comments.
This debacle has caused a stir with coutries worldwide, with US senators calling on Mr Zuckerberg to testify before Congress, consumer watchdog, the US Federal Trade Commission, has reportedly opened an investigation into Facebook, and the head of the European Parliament has requested an investigation to see if the data was misused.
In the UK, Information Commissioner, Elizabeth Denham, is attempting to obtain a warrant to search the offices of Cambridge Analytica and a UK parliamentary committee has called for Zuckerberg to give evidence regarding how Facebook uses personal data.
Trump's campaign isn't the only piece of politics that Cambridge Analytica has been involved it. There are also calls for the work they did during the 2013 election in Kenya to be investigated.