As of April 2018, Facebook has implemented a new privacy feature that allows users to control who can see their profile. Additionally, anyone who tries to view your profile will be prompted to request permission from you before they can see any of your content. This change is in response to the Cambridge Analytica scandal, in which it was revealed that personal data from 87 million Facebook users had been improperly accessed by a third-party political consulting firm.
Under the new privacy settings, users can choose to make their profile completely private, meaning that only friends who have been approved by the user will be able to see their content. Non-friends who try to view the user's profile will only be able to see their name and profile picture (if they have one). Additionally, all posts and comments from private profiles will only be visible to approved friends.
This change is a major shift for Facebook, which has traditionally been an open platform where anyone could see your content unless you specifically restricted it. The new privacy settings give users much more control over who can see their content, and should help to address some of the concerns about how Facebook handles data privacy.