How to make authorization on android?

Question

Android

How to make authorization on android? So that there is authorization through VK.com, Google, Facebook, your user database, into which new users will be replenished through the registration page in the application.

Answer 1

Use the backend, interact with the backend with the application through the API.
Authorization and storage on the back side, application only for output and display logic.

Answer 2

To get started, you can try Fireebase, a lot of information about how to register + can be stored on their server