Firebase Overview

Here are some overview of Firebase Features:

Firebase analytics:

Firebase Analytics collects usage and behavior data for your app.

Firebase cloud messaging:

Using FCM, you can notify a client app that new email or other data is available to sync. You can send notification messages to drive user re-engagement and retention. For use cases such as instant messaging, a message can transfer a payload of up to 4 KB to a client app.
FCM: Firebase cloud messaging (Updated form of GCM)

Firebase Authentication:

Most apps need to know the identity of a user. Knowing a user's identity allows an app to securely save user data in the cloud and provide the same personalized experience across all of the user's devices.

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

Firebase Realtime Database:

Store and sync data with our NoSQL cloud database. Data is synced across all clients in realtime, and remains available when your app goes offline.

The Firebase Realtime Database is a cloud-hosted database. Data is stored as JSON and synchronized in realtime to every connected client. When you build cross-platform apps with our iOS, Android, and JavaScript SDKs, all of your clients share one Realtime Database instance and automatically receive updates with the newest data.

Firebase Storage:

Firebase Storage lets you upload and share user generated content, such as images and video, which allows you to build rich media content into your apps. Firebase Storage stores this data in a Google Cloud Storage bucket, a petabyte scale object storage solution with high availability and global redundancy. Firebase Storage lets you securely upload these files directly from mobile devices and web browsers, handling spotty networks with ease.

Firebase Test Lab for Android:

Test your app on devices hosted in a Google datacenter.