Facebook are set to alert 87 million users at noon today (April 9) that their data has been shared with political consulting firm Cambridge Analytica.
Though the majority of affected users are thought to be from the United States, roughly 1 million users from the UK have also been affected.
How to know if you have been affected
Users affected by the data-harvesting scheme, will be provided a notification from Facebook title Protecting Your Information.
The following message will appear at the top of their news feeds and read: "(User Name), we understand the importance of keeping your data safe.
"We have banned the website: “This is Your Digital Life” which one of your friends used Facebook to log into. We did this because the website may have misused some your Facebook information by sharing it with a company called Cambridge Analytica.
"You can learn more about what happened and how you can remove other apps and websites anytime if you no longer want them to have access to your information.
"There is more work to do, but we are committed to confronting abuse and to putting you in control of your privacy."
Facebook users will be provided one of the following two options (Photo: Facebook)
Users are then provided the options to “See how you’re affected”.
The remaining users whose information wasn't shared with Cambridge Analytica will receive a notice reading: "(User name), we understand the importance of keeping your data safe, and are making it easier for you to control which apps you share information with.
"You can go to the Apps and Websites section of your settings anytime to see the apps and websites you’ve used Facebook to log into. You can also remove the ones you don’t want connected to Facebook anymore."
Facebook users will then be provided a link to a list of apps and websites which posses their data.
This Is Your Digital Life
Though Mark Zuckerburg has calculated that roughly 87 million users were affected by the Cambridge Analytica strategy of data harvesting, he admitted there was no way to know for sure how many users were affected.
The Facebook CEO revealed that Facebook came up with the figure by calculating the maximum number of friends that users could have had while Mr Kogan's app was collecting data.
The company, however, does not have logs going back that far, he admitted, so it cannot know exactly how many people may have been affected.
This Is Your Digital Life, was a personality quiz created in 2014 by an academic researcher named Aleksander Kogan, who paid about 270,000 people to take it.
The app vacuumed up not just the data of the people who took it, but also - thanks to Facebook's loose restrictions - data from friends, too. This included sensitive details that affected users hadn't intended to share publicly.