Like any organization providing services to users in European Union countries, Facebook is bound by the EU General Data Protection Regulation (GDPR). Due to the scrutiny Facebook is already facing regarding the Cambridge Analytica scandal, as well as the general nature of the social media giant’s product being personal information, its strategy for GDPR compliance is similarly receiving a great deal of focus from users and other companies looking for a model of compliance…Facebook members outside the US and Canada have heretofore been governed by the company’s terms of service in Ireland. This has reportedly been changed prior to the start of GDPR enforcement, as this would seemingly make Facebook liable for damages for users internationally, due to Ireland’s status as an EU member.

“Shadow profiles” are stores of information that Facebook has obtained about other people—who are not necessarily Facebook users. The existence of “shadow profiles” was discovered as a result of a bug in 2013. When a user downloaded their Facebook history, that user would obtain not just his or her address book, but also the email addresses and phone numbers of their friends that other people had stored in their address books…Because of the way that Facebook synthesizes data in order to attribute collected data to existing profiles, data of people who do not have Facebook accounts congeals into dossiers, which are popularly called a “shadow profile.” It is unclear what other sources of input are added to said “shadow profiles,” a term that Facebook does not use, according to Zuckerberg in his Senate testimony.

–Facebook data privacy scandal: A cheat sheet, Tech Republic, By James Sanders and Dan Patterson, June 14, 2018