Too Long; Didn't Read
The underlying protocol used is something called OAuth. It is defined by this website as: "An open protocol to allow secure authorization in a simple and standard method from web, mobile and desktop applications" Social logins help us achieve the following:Support for multiple devices; single Sign-On; simple to implement; Simple to implement. The ability to share data for users without having to release personal information;Ability to revoke an active session i.e not allow third-party access to the login and data; There are no long-lasting credentials being exchanged.