What is Firebase authentication in Flutter?

Firebase Authentication provides backend services & easy-to-use SDKs to authenticate users to your app . It supports authentication using passwords, phone numbers, popular federated identity providers like Google, Facebook and Twitter, and more.

Implementing Firebase Authentication in a Flutter app

There are many ways of keeping user signed-in to a flutter application. In this tutorial we going to use firebase Auth method authStateChanges(). Firebase Auth enables you to subscribe in realtime to this state via a Stream .