Firebase UI is completely open source and easily customizes to fit in with your app that includes some set of libraries. It allows you to quickly connect UI elements to the Firebase database for data storage, allowing views to be updated in Realtime, and it also provides the simple interfaces for common tasks such as displaying lists or collections of items.

FirebaseUI Auth is a recommended way to add authentication in Firebase app, or we can do it manually with Firebase Authentication SDK. It allows users to add a complete UI flow for signing in with email and passwords, phone numbers, and with most popular identity providers, including Google and Facebook Login.

FirebaseUI is available at https://opensource.google.com/projects/firebaseui.

We will explore more about Authentication in detail in the upcoming chapters.