Facebook always help maintain the privacy of its users. By this way Facebook has introduced the Anonymous Login feature. So that people do not over share personal information.
But In the previous setup, to share personal data this feature available on Facebook with third-party applications, in order to gain access to apps such as Candy Crush. A user did not have the discretion of choosing which information they wanted to share. All that is about to change thanks to the Anonymous Login feature.
On April 30, 2014, Facebook announced that it would introduce a new API next spring, By this Anonymous Login feature the user and the developer, able to choose what information the app can access. For this Anonymous Login feature the Developers were given a one-year window to prepare for the change.
After one year later, Facebook prove its promise. Users who now access any third-party app using the "Log In Using Facebook" feature will be guided to a login approval page where they will be greeted by the option of choosing which data sets they are willing to share.
So thanks a lot to Facebook for introducing this new feature.